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  • 1.
    A. Sani, Negar
    Linköping University, Department of Science and Technology, Physics and Electronics.
    M-PSK and M-QAM Modulation/Demodulation of UWB Signal Using Six-Port Correlator2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays high speed and high data rate communication are highly demanded. Consequently, wideband and high frequency transmitter and receivers should be designed. New transmitters and receivers should also have low power consumption, simple design and low manufacturing price in order to fulfill manufacturers’ requests for mass production. Having all above specifications, six-port correlator is a proper choice to be used as modulator and demodulator in transmitters and receivers.

    In this thesis the six-port correlator is introduced, modeled and simulated using Advanced Design System (ADS) software. A simple six-port transmitter/receiver system with a line of sight link is modeled and analyzed in BER, path length and noise terms. The modulation in this system is QAM, frequency is 7.5 GHz and symbol rate is 500 Msymbol/s.

    Furthermore two methods are proposed for high frequency and high symbol rate M-PSK and M-QAM modulation using six-port correlator. The 7.5 GHz modulators are modeled and simulated in ADS. Data streams generated by pseudo random bit generator with 1 GHz bandwidth are applied to modulators. Common source field effect transistors (FETs) with zero bias are used as controllable impedance termination to apply baseband data to modulator. Both modulators show good performance in M-PSK and M-QAM modulation.

  • 2.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence2013In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, no 320Article in journal (Refereed)
    Abstract [en]

    Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

  • 3.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study2014In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 7, no 1, 430-440 p.Article in journal (Refereed)
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

  • 4.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khan, Azam
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fabrication of UV photo-detector based on coral reef like p-NiO/n-ZnO nanocomposite structures2013In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 108, 149-152 p.Article in journal (Refereed)
    Abstract [en]

    In this research work, a UV photo-detector is fabricated on fluorine doped tin oxide (FTO) glass substrate by exploiting the advantageous features of p-n heterojunctions based on p-NiO and n-ZnO composite nanostructures forming a coral-reef like structures. Scanning electron microscopy (SEM) and X-ray diffraction results showed uniform morphology and good crystal quality of the synthesised nanostructures respectively. I-V measurements have shown nonlinear and rectifying response of the p-NiO/n-ZnO heterojunction. The proposed photodiode exhibited excellent UV response with acceptable photocurrent generation of about 3.4 mA and the responsivity of 2.27 A/W at -3 biasing voltage.

  • 5.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khan, Yaqoob
    National Centre for Physics, Islamabad, Pakistan .
    Khan, Azam
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Iron (III) Ion Sensor Based on the Seedless Grown ZnO Nanorods in 3 Dimensions Using Nickel Foam Substrate2013In: Journal of Sensors, ISSN 1687-725X, E-ISSN 1687-7268, no 382726Article in journal (Refereed)
    Abstract [en]

    In the present work, the seedless, highly aligned and vertical ZnO nanorods in 3 dimensions (3D) were grown on the nickel foam substrate. The seedless grown ZnO nanorods were characterised by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) techniques. The characterised seedless ZnO nanorods in 3D on nickel foam were highly dense, perpendicular to substrate, grown along the (002) crystal plane, and also composed of single crystal. In addition to this, these seedless ZnO nanorods were functionalized with trans-dinitro-dibenzo-18-6 crown ether, a selective iron (III) ion ionophore, along with other components of membrane composition such as polyvinyl chloride (PVC), 2-nitopentylphenyl ether as plasticizer (NPPE), and tetrabutyl ammonium tetraphenylborate (TBATPB) as conductivity increaser. The sensor electrode has shown high linearity with a wide range of detection of iron (III) ion concentrations from 0.005 mM to 100 mM. The low limit of detection of the proposed ion selective electrode was found to be 0.001 mM. The proposed sensor also described high storage stability, selectivity, reproducibility, and repeatability and a quick response time of less than 10 s.

  • 6.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khan, Yaqoob
    Quaid-e-Azam University Campus, Islamabad, Pakistan.
    Khan, Azam
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures2012In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, no 11, 15424-15437 p.Article in journal (Refereed)
    Abstract [en]

    In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples.

  • 7.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khan, Yaqoob
    National Centre for Physics, Quaid-e-Azam University Campus, Islamabad, Pakistan .
    Hussain, Sajjad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Anions effect on the low temperature growth of ZnO nanostructures2012In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 12, 1998-2001 p.Article in journal (Refereed)
    Abstract [en]

    Seed mediated aqueous chemical growth (ACG) route was used for the growth of ZnO nanostructures on Si substrate in four different growth mediums. The growth medium has shown to affect the morphology and the size of the different nanostructures. We observed that the medium containing zinc nitrate anions yields the nanorods, in a medium containing zinc acetate anions nano-candles are obtained. While in a medium containing zinc chloride anions ZnO nano-discs were obtained and in a medium containing zinc sulfate anions nano-flakes are achieved. Growth in these different mediums has also shown effect on the optical emission characteristics of the different ZnO nanostructures.

  • 8.
    Abbasi, Muneeb Mehmood
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Jabbar, Mohammad Abdul
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Design and Performance Analysis of Low-Noise Amplifier with Band-Pass Filter for 2.4-2.5 GHz2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Low power wireless electronics is becoming more popular due to durability, portability and small dimension. Especially, electronic devices in instruments, scientific and medical (ISM) band is convenient from the spectrum regulations and technology availability point of view. In the communication engineering society, to make a robust transceiver is always a matter of challenges for the better performance.

    However, in this thesis work, a new approach of design and performance analysis of Low-Noise Amplifier with Band-Pass filter is performed at 2.45 GHz under the communication electronics research group of Institute of Science and Technology (ITN). Band-Pass Filtered Low-Noise Amplifier is designed with lumped components and transmission lines. Performances of different designs are compared with respect to noise figure, gain, input and output reflection coefficient. In the design process, a single stage LNA is designed with amplifier, ATF-58143. Maximally flat band-pass (BPF) filters were designed with lumped components and distributed elements. Afterwards, BPF is integrated with the LNA at the front side of LNA to get a compact Band-Pass Filtered Low-Noise Amplifier with good performance.

    Advanced Design System (ADS) tool was used for design and simulation, and each design was tuned to get the optimum value for noise figure, gain and input reflection coefficient. LNA stand-alone gives acceptable value of noise figure and gain but the bandwidth was too wide compared to specification. Band-Pass Filtered Low-Noise Amplifier with lumped components gives also considerable values of noise and gain. But the gain was not so flat and the bandwidth was also wide. Then, Band-Pass Filtered Low-Noise Amplifier was designed with transmission lines where the optimum value of noise figure and gain was found. The gain was almost flat over the whole band, i.e., 2.4-2.5 GHz compared to LNA stand-alone and Band-Pass Filtered Low-Noise Amplifier designed with lumped components. It is observed that deviations of results from schematic to layout level are considerable, i.e., electromagnetic simulation is needed to predict the Band-Pass Filtered Low-Noise Amplifier performance.

    Prototype of LNA, Band-Pass Filtered Low-Noise Amplifier with lumped and transmission lines are made at ITN’s PCB laboratory. Due to unavailability of exact values of Murata components and for some other technical reasons, the measured values of Band-Pass Filtered Low-Noise Amplifier with lumped components and transmission lines are deviated compared to predicted values from simulation.

  • 9.
    Abdalla, Hassan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Investigation of the dimensionality of charge transport in organic field effect transistors2017In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 8, 85301Article in journal (Refereed)
    Abstract [en]

    Ever since the first experimental investigations of organic field effect transistors (OFETs) the dimensionality of charge transport has alternately been described as two dimensional (2D) and three dimensional (3D). More recently, researchers have turned to an analytical analysis of the temperature-dependent transfer characteristics to classify the dimensionality as either 2D or 3D as well as to determine the disorder of the system, thereby greatly simplifying dimensionality investigations. We applied said analytical analysis to the experimental results of our OFETs comprising molecularly well-defined polymeric layers as the active material as well as to results obtained from kinetic Monte Carlo simulations and found that it was not able to correctly distinguish between 2D and 3D transports or give meaningful values for the disorder and should only be used for quasiquantitative and comparative analysis. We conclude to show that the dimensionality of charge transport in OFETs is a function of the interplay between transistor physics and morphology of the organic material.

  • 10.
    Abdollahi Sani, Negar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Robertsson, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Cooper, Philip
    De La Rue Plc, Overton, Hampshire, UK .
    Wang, Xin
    Acreo AB, Norrköping, Sweden.
    Svensson, Magnus
    Acreo AB, Norrköping, Sweden.
    Andersson Ersman, Peter
    Acreo AB, Norrköping, Sweden.
    Norberg, Petronella
    Acreo AB, Norrköping, Sweden.
    Nilsson, Marie
    Acreo AB, Norrköping, Sweden.
    Nilsson, David
    Acreo AB, Norrköping, Sweden.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Hesselbom, Hjalmar
    Hesselbom Innovation and Development HB, Huddinge, Sweden .
    Akesso, Laurent
    De La Rue Plc, Overton, Hampshire, UK .
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Acreo AB, Norrköping, Sweden.
    Gustafsson, Goran
    Acreo AB, Norrköping, Sweden.
    All-printed diode operating at 1.6 GHz2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 33, 11943-11948 p.Article in journal (Refereed)
    Abstract [en]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.

  • 11.
    Abdollahi Sani, Negar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Xin
    Acreo Swedish ICT AB, Sweden.
    Granberg, Hjalmar
    INNVENTIA AB, Sweden.
    Andersson Ersman, Peter
    Acreo Swedish ICT AB, Sweden.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Dyreklev, Peter
    Acreo Swedish ICT AB, Sweden.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Göran
    Acreo Swedish ICT AB, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Flexible Lamination-Fabricated Ultra-High Frequency Diodes Based on Self-Supporting Semiconducting Composite Film of Silicon Micro-Particles and Nano-Fibrillated Cellulose2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 28921Article in journal (Refereed)
    Abstract [en]

    Low cost and flexible devices such as wearable electronics, e-labels and distributed sensors will make the future "internet of things" viable. To power and communicate with such systems, high frequency rectifiers are crucial components. We present a simple method to manufacture flexible diodes, operating at GHz frequencies, based on self-adhesive composite films of silicon micro-particles (Si-mu Ps) and glycerol dispersed in nanofibrillated cellulose (NFC). NFC, Si-mu Ps and glycerol are mixed in a water suspension, forming a self-supporting nanocellulose-silicon composite film after drying. This film is cut and laminated between a flexible pre-patterned Al bottom electrode and a conductive Ni-coated carbon tape top contact. A Schottky junction is established between the Al electrode and the Si-mu Ps. The resulting flexible diodes show current levels on the order of mA for an area of 2 mm(2), a current rectification ratio up to 4 x 10(3) between 1 and 2 V bias and a cut-off frequency of 1.8 GHz. Energy harvesting experiments have been demonstrated using resistors as the load at 900 MHz and 1.8 GHz. The diode stack can be delaminated away from the Al electrode and then later on be transferred and reconfigured to another substrate. This provides us with reconfigurable GHz-operating diode circuits.

  • 12.
    Aftab, A.
    et al.
    Petroleum and Natural Gas Engineering Department, Mehran UETSZAB Sindh, Pakistan; Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Malaysia.
    Ismail, A. R.
    Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Malaysia.
    Khokhar, S.
    Quaid-e-Awam University of Engineering, Science and Technology, Sindh Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Institute of Chemistry, University of Sindh Jamshoro, Sindh Pakistan.
    Novel zinc oxide nanoparticles deposited acrylamide composite used for enhancing the performance of water-based drilling fluids at elevated temperature conditions2016In: Journal of Petroleum Science and Engineering, ISSN 0920-4105, E-ISSN 1873-4715, Vol. 146, 1142-1157 p.Article in journal (Refereed)
    Abstract [en]

    Multifunctional nano-micron composite compared to single nano-sphere materials revealed wide applications to enhance the physical and chemical stability of base fluids. Therefore, it can be a possible solution for the improvement of the rheological properties and shale inhibition characteristics of conventional water-based drilling fluid (WBDF). The primary goal of the study was to investigate the effects zinc oxide nanoparticles-acrylamide composite termed as ZnO-Am composite over rheological and shale swelling behavior of conventional WBDF. Herein, ZnO-Am composite was synthesized and successfully characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermalgravimeteric analysis (TGA), scanning electron microscope (SEM) and field emission electron microscope (FESEM). Results revealed that the rheological properties such as 10-min gel strength (10-min GS), apparent viscosity (AV), and plastic vicscocity (PV) were slightly increased and obtained within operating range at 150 degrees F by adding the synthesized composite in conventional WBDF. Lubricity was improved by 25% at 150 degrees F. API filtrate loss volume was reduced by 14%. Elevated temperature and pressure (ETP) filtrate loss volume (500 psi, 250 degrees F) was slightly minimized. Shale swelling was merely reduced from 16% to 9%. These findings will contribute to enhance the oil and gas well drilling operations.

  • 13.
    Aghel Dawood, Menhel
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Obradovic, Dragan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Guidelines for control equipment2013Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete är utfört på ABB LV System som är en del av företaget ABB i Sverige. Detta är ett företag som bygger kontrollutrustning till kunder som befinner sig i många delar av världen. Vår uppgift var att sätta samman en pärm med riktlinjer för montörerna.

    Pärmen ska vara lättläst och samtidigt innehålla alla standarder samt viktig fakta som kan behövas vid byggandet av kontrollutrustning.

    Riktlinjerna som framställts ledde till att montörerna blev bättre uppdaterade om de senaste riktlinjerna och standarder som leder idag. Tack vara att montörerna nu har allt samlat i en lättläslig pärm blir ledtiderna kortare.

  • 14.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Hui
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric Properties of Polymeric Mixed Conductors2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 34, 6288-6296 p.Article in journal (Refereed)
    Abstract [en]

    The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion-electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (Voc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT-PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the Voc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of Voc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor

  • 15.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ullah Khan, Zia
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Granberg, Hjalmar
    Innventia AB, Sweden.
    Berthold, Fredrik
    Innventia AB, Sweden.
    Parasuraman, Rajasekar
    Mat Research Centre, India.
    Urnarji, Arun M.
    Mat Research Centre, India.
    Slettengren, Kerstin
    Innventia AB, Sweden.
    Pettersson, Henrik
    Innventia AB, Sweden.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Room temperature synthesis of transition metal silicide-conducting polymer micro-composites for thermoelectric applications2017In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 225, 55-63 p.Article in journal (Refereed)
    Abstract [en]

    Organic polymer thermoelectrics (TE) as well as transition metal (TM) silicides are two thermoelectric class of materials of interest because they are composed of atomic elements of high abundatice; which is a prerequisite for mass implementation of thermoelectric (TE) solutions for solar and waste heat recovery. But both materials have drawbacks when it comes to finding low-cost manufacturing. The metal silicide needs high temperature (amp;gt;1000 degrees C) for creating TE legs in a device from solid powder, but it is easy to achieve long TE legs in this case. On the contrary, organic TEs are synthesized at low temperature from solution. However, it is difficult to form long legs or thick films because of their low solubility. In this work, we propose a novel method for the room temperature synthesis of TE composite containing the microparticles of chromium disilicide; CrSi2 (inorganic filler) in an organic matrix of nanofibrillated cellulose-poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (NFC-PEDOT:PSS). With this method, it is easy to create long TE legs in a room temperature process. The originality of the approach is the use of conducting polymer aerogel microparticles mixed with CrSi2 microparticles to obtain a composite solid at room temperature under pressure. We foresee that the method can be scaled up to fabricate and pattern TE modules. The composite has an electrical conductivity (sigma) of 5.4 +/- 0.5 S/cm and the Seebeck coefficient (a) of 88 +/- 9 mu V/K, power factor (alpha(2)sigma) of 4 +/- 1 mu Wm(-1) K-2 at room temperature. At a temperature difference of 32 degrees C, the output power/unit area drawn across the load, with the resistance same as the internal resistance of the device is 0.6 +/- 0.1 mu W/cm(2). (C) 2017 Elsevier B.V. All rights reserved.

  • 16.
    Alghazi, Ziad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Wireless instrumentation2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Syftet med detta examensarbete var att undersöka om det finns möjlighet att implementera en trådlöst instrumenterings kit från Emerson Rosemount Process AB på dagens styrsystem som finns på Siemens gasturbiner. En prototyp skapades som bygger på Siemens Simatic PCS-7 med en styrenhet och en switch. Där efter implementerades Emerson Wireless gateway och två trådlösa instrument. I examanearbetet skapades även en logik som hanterar kommunikationen mellan simatic och gateway. Modbus RTU och TCP/IP är kommunikationsprotokollet som användes under arbetet. En undersökning om den uppsättningen klarar av de atex (ATmosphères EXplosibles )och sil (saftey integrity level ) krav gjordes, för att säkerställa om det finns möjligheter att implementera detta på dagens tillverkningsprocess. Utöver dessa kontrollerades om det råder för och nackdelar med den trådlösa allternativet inom IT-säkerhet, instrumentdiagnostik och störkänslighet. Arbetet fullgjordes på Siemens Industrial Turbomachinery i Finspång tillsammans med företagets utvecklingsavdelning för styrsystem.

  • 17.
    Ali, A.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Bahauddin Zakriya University, Multan, Pakistan.
    AlSalhi, M. S.
    King Saud University, Riyadh, Saudi Arabia and Bahauddin Zakriya University, Multan, Pakistan.
    Atif, M.
    King Saud University, Riyadh, Saudi Arabia.
    Ansari, Anees A.
    King Saud University, Riyadh, Saudi Arabia.
    Israr, Muhammad Qadir
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sadaf, J. R.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ahmed, E.
    Bahauddin Zakriya University, Multan, Pakistan.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Potentiometric urea biosensor utilizing nanobiocomposite of chitosan-iron oxide magnetic nanoparticles2013In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 414Article in journal (Refereed)
    Abstract [en]

    The iron oxide (Fe3O4) magnetic nanoparticles have been fabricated through a simple, cheap and reproducible approach. Scanning electron microscope, x-rays powder diffraction of the fabricated nanoparticles. Furthermore, the fabrication of potentiometric urea biosensor is carried out through drop casting the initially prepared isopropanol and chitosan solution, containing Fe3O4 nanoparticles, on the glass fiber filter with a diameter of 2 cm and a copper wire (of thickness −500 μm) has been utilized to extract the voltage signal from the functionalized nanoparticles. The functionalization of surface of the Fe3O4 nanoparticles is obtained by the electrostatically immobilization of urease onto the nanobiocomposite of the chitosan- Fe3O4 in order to enhance the sensitivity, specificity, stability and reusability of urea biosensor. Electrochemical detection procedure has been adopted to measure the potentiometric response over the wide logarithmic concentration range of the 0.1 mM to 80 mM. The Fe3O4 nanoparticles based urea biosensor depicts good sensitivity with ~42 mV per decade at room temperature. Durability of the biosensor could be considerably enhanced by applying a thin layer of the nafion. In addition, the reasonably stable output response of the biosensor has been found to be around 12 sec.

  • 18.
    Ali, A.
    et al.
    Riphah Int University, Pakistan.
    Israr-Qadir, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wazir, Z.
    Riphah Int University, Pakistan.
    Tufail, M.
    Riphah Int University, Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Jamil-Rana, Sadaf
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Atif, M.
    King Saud University, Saudi Arabia; National Institute Lasers and Optron, Pakistan.
    Khan, S. A.
    National Centre Phys, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Cobalt oxide magnetic nanoparticles-chitosan nanocomposite based electrochemical urea biosensor2015In: Indian Journal of Physics, ISSN 0973-1458, E-ISSN 0974-9845, Vol. 89, no 4, 331-336 p.Article in journal (Refereed)
    Abstract [en]

    In this study, a potentiometric urea biosensor has been fabricated on glass filter paper through the immobilization of urease enzyme onto chitosan/cobalt oxide (CS/Co3O4) nanocomposite. A copper wire with diameter of 500 mu m is attached with nanoparticles to extract the voltage output signal. The shape and dimensions of Co3O4 magnetic nanoparticles are investigated by scanning electron microscopy and the average diameter is approximately 80-100 nm. Structural quality of Co3O4 nanoparticles is confirmed from X-ray powder diffraction measurements, while the Raman spectroscopy has been used to understand the chemical bonding between different atoms. The magnetic measurement has confirmed that Co3O4 nanoparticles show ferromagnetic behavior, which could be attributed to the uncompensated surface spins and/or finite size effects. The ferromagnetic order of Co3O4 nanoparticles is raised with increasing the decomposition temperature. A physical adsorption method is adopted to immobilize the surface of CS/Co3O4 nanocomposite. Potentiometric sensitivity curve has been measured over the concentration range between 1 x 10(-4) and 8 x 10(-2) M of urea electrolyte solution revealing that the fabricated biosensor holds good sensing ability with a linear slope curve of similar to 45 mV/decade. In addition, the presented biosensor shows good reusability, selectivity, reproducibility and resistance against interferers along with the stable output response of similar to 12 s.

  • 19.
    Ali Abbasi, Mazhar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction2013Manuscript (preprint) (Other academic)
    Abstract [en]

    The electron transport in the electronic devices has significant influence on the device performance, thus current transport properties determination is highly demanded for a particular device. Herein, we report the facile hydrothermal growth method based fabrication of p-NiO/n-ZnO heterojunction. The material characterization was performed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy. These techniques provided the good crystal quality, pure phase of p-NiO and n-ZnO nanostructures respectively. The measured valance band offset of composite nanostructure is 2.25 eV and conduction band offset was found to be 2.58 eV. The current transport properties of the fabricated p-n junction are governed by three different I-V regions. The impedance spectroscopy was used for the determination of the role of grain boundaries at the interface.

  • 20.
    Ali, Akbar
    et al.
    Riphah Int University, Pakistan.
    Fakhar-E-Alam, Muhammad
    GC University, Pakistan.
    Abbas, Najeeb
    GC University, Pakistan.
    Wazir, Zafar
    Riphah Int University, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Tufail, Muhammad
    Riphah Int University, Pakistan.
    Atif, M.
    King Saud University, Saudi Arabia; National Institute Laser and Optron, Pakistan.
    Silver-chitosan nanobiocomposite as urea biosensor2014In: Optoelectronics and Advanced Materials Rapid Communications, ISSN 1842-6573, E-ISSN 2065-3824, Vol. 8, no 11-12, 1238-1242 p.Article in journal (Refereed)
    Abstract [en]

    Silver nanoparticles (Ag NPs) were synthesized by aqueous chemical growth technique. The above mentioned synthesized materials were characterized by applying scanning electron microscope (SEM) and X-ray diffraction for confirmation of morphological analysis, compositional purity, and crystalline property and emission characteristics as well. In order to fabricate the urea biosensor (potentiometric), a solution of deionized water and chitosan was prepared having Ag NPs. The said solution was dropped on the glass fiber filter having diameter of 2 cm. A wire of copper having thickness of approximately 500 pm was used for the voltage signal to pull out from the said working nanoparticles (NPs). To improve the strength, sensitivity and the quality of the potentiometric urea biosensor, a specific functional surface of Ag NPs was attained by electrostatic restrained of an enzyme (urease) onto the chitosan-Ag (a nanobiocomposite). The potentiometric reaction was measured via electrochemical detection technique. The potentiometric urea biosensor illustrates significant sensibility at room temperature with approximate to 42 mV as per span. Furthermore, the said biosensor showed an appropriate stable response within 7 sec.

  • 21.
    Ali, Islam
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Iqbal, Wasim
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Performance analysis of various antennas at 2.45 GHz2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this era of technology, there is a swift increase in the number of applications which operate at the Industrial Scientific Medical Band. The applications of this band ranges from home microwave oven to wireless local area networks (WLAN). Therefore, the design of antennas on this band is essential.

    This thesis work revolves around the detailed study and design of various antennas at 2.45 GHz. All the simulation of the antennas was performed using advanced design system (ADS). Microstrip antenna technology is commonly used in antenna design due to its advantages such as low-profile, small size and easy fabrication on printed circuit boards.

    Firstly, various antennas such as rectangular patch, square patch, dipole, inverted F and printed Yagi were designed using ADS and their different performance parameters such as input impedance matching, voltage standing wave ratio (VSWR), input reflection, and gain and directivity were discussed. Dipole antenna, inverted F and printed Yagi were fabricated on printed circuit board (PCB) to compare their measured and simulated results.

    At the end, a conclusion is drawn for different antennas based on their various performance parameters.

  • 22.
    Ali Soomro, Razium
    et al.
    University of Sindh, Pakistan.
    Hallam, Keith Richard
    University of Bristol, UK.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Juddin, Siraj
    University of Sindh, Pakistan.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Glutaric Acid Assisted Fabrication of CuO Nanostructures and their Application in Development of Highly Sensitive Electrochemical Sensor System for Carbamates2016In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 28, no 7, 1634-1640 p.Article in journal (Refereed)
    Abstract [en]

    This work describes the fabrication of unique arrow head shaped CuO nanostructures using simple hydrothermal treatment method. The highly attractive features were obtained by the application of glutaric acid utilised simultaneous as template and functionalising agent. The functionalised nanostructures were known to possess excellent potential towards the electro-catalytic oxidation of carbofuran pesticide. The generated intense electrochemical signal with lower potential value enabled sensitive and selective determination of carbofuran up to 1 x 10(-3) mu M with wide sensing window in range of 0.01 to 0.16 mu M. The feasibility of the developed sensor system for the practical application was also studied by testing its potential in real sample extracts of various vegetables. The excellent recoveries demonstrated the analytical robustness of the developed sensor system. The sensor system utilises a new and simple approach towards sensitive determination of toxic pesticides reflecting its wide spectrum application in various fields.

  • 23.
    Ali Soomro, Razium
    et al.
    University of Sindh, Pakistan.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Sirajuddin,
    University of Sindh, Pakistan.
    Ishaq Abro, Muhammad
    Mehran University of Engineering & Technology, Pakistan .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Controlled synthesis and electrochemical application of skein-shaped NiO nanostructures2015In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, no 3, 913-922 p.Article in journal (Refereed)
    Abstract [en]

    A simple, economical and mild solution chemistry method was used to synthesize diverse nickel oxide (NiO) nanostructures employing methionine as a growth-directing agent. The as-synthesized NiO nanostructures were observed to possess a unique skein-shape morphology with uniform spherical distribution. The NiO nanoskein (NiO NSk) formation was extensively studied using X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) techniques, respectively. The unique NiO NSks exhibited better electrocatalytic activity towards glucose oxidation in alkaline media, enabling the development of a highly sensitive non-enzymatic glucose sensor. The observed analytical properties included high sensitivity (1915 mu A mM(-1) cm(-2)), wide linear range (0.1-5.0 mM), low detection limit (0.7 mu M), higher stability and reproducibility. Moreover, the sensor is selective in the presence of interfering species such as ascorbic acid (AA), uric acid (UA) and dopamine (DP) during the non-enzymatic glucose sensing. The worthy-of-notice electrocatalytic activity and economical feasible preparation of NiO NSk-shaped electroactive material for direct glucose-sensing applications make the present study of high interest for the fabrication of low-cost devices. A NiO NSk-based glucose sensor has also been employed for glucose determination in human serum with adequate results, suggesting high potential for the routine monitoring of glucose from biotechnology, clinical and food industry samples.

  • 24.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Hussain Ibupoto, Zafar
    Dr MA Kazi Institute Chemistry University of Sindh, Pakistan.
    Tufail Hussain Sirajuddin; Sherazi, Syed
    University of Sindh, Pakistan.
    Ishaq Abro, Muhammad
    Mehran University of Engn and Technology, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Practice of diclofenac sodium for the hydrothermal growth of NiO nanostructures and their application for enzyme free glucose biosensor2016In: Microsystem Technologies: Micro- and Nanosystems Information Storage and Processing Systems, ISSN 0946-7076, E-ISSN 1432-1858, Vol. 22, no 10, 2549-2557 p.Article in journal (Refereed)
    Abstract [en]

    In this study diclofenac sodium (DFS), an analgesic drug has been employed as an effective template for the synthesis of NiO nanostructures. The NiO nanostructures were synthesised using low temperature hydrothermal growth method, both in the presence and absence of the DFS drug. The synthesised nanostructures were studied for their structural, compositional and electrochemical properties using scanning electron microscopy, X-ray diffraction and cyclic voltammetry. The synthesised nanostructures were then utilised for the modification of glassy carbon electrode which were then utilised for the electro-catalytic enzyme free glucose sensing in alkaline media. The competitive experiments suggested that although, both nanostructures possess excellent capability of glucose sensing, the NiO nanoflakes modified electrode was found to be twice as much as sensitive (2584 A mu A mM(-1) cm(-2)) as nanoflowers based electrode (1154 A mu A mM(-1) cm(-2)). The NiO nanoflakes based sensor further demonstrated excellent anti-interference potential in the presence of common interferents like uric acid, ascorbic acid and dopamine. In addition, the successful application NiO nanoflakes based sensor to determine real blood glucose concentration further suggest its feasibility for real sample analysis.

  • 25.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tufail Hussain Sirajuddin; Sherazi, Syed
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Ishaq Abro, Muhammad
    Mehran University of Engn and Technology, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ahmed Mahesar, Sarfaraz
    University of Sindh, Pakistan.
    Hussain Kalwar, Nazar
    University of Sindh, Pakistan.
    Glycine-assisted preparation of Co3O4 nanoflakes with enhanced performance for non-enzymatic glucose sensing2015In: MATERIALS EXPRESS, ISSN 2158-5849, Vol. 5, no 5, 437-444 p.Article in journal (Refereed)
    Abstract [en]

    In this study a simple, inexpensive and efficient route is proposed to synthesise attractive cobalt oxide (Co3O4) nanostructures using glycine as an effective growth controller and regulator. The as-synthesised Co3O4 nanostructures were observed to possess unique nanoflake shape morphological features with highly dense distribution. The formation of Co3O4 nanoflakes (Co3O4 NFKs) was elaborately explored using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM) respectively. The unique Co3O4 nanoflakes were known to possess excellent electro-catalytic potential for the oxidation of glucose in alkaline medium. This potential property allowed successful development of highly sensitive (1180 mu A mM(-1) cm(-2)), selective and stable non-enzymatic glucose sensor. In addition, the developed sensor had a wide working range (0.1-5.0 mM), low limit of detection (0.7 mu M), and excellent reproducibility, besides the capability of analysing real blood glucose samples.

  • 26.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Nafady, Ayman
    King Saud University, Saudi Arabia; Sohag University, Egypt.
    Hallam, Keith Richard
    University of Bristol, England.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Al Enizi, Abdullah
    King Saud University, Saudi Arabia.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sirajuddin,
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Dr MA Kazi Inst Chem, Jamshoro 76080, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Highly sensitive determination of atropine using cobalt oxide nanostructures: Influence of functional groups on the signal sensitivity2016In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 948, 30-39 p.Article in journal (Refereed)
    Abstract [en]

    This study describes sensitive determination of atropine using glassy carbon electrodes (GCE) modified with Co3O4 nanostructures. The as-synthesised nanostructures were grown using cysteine (CYS), glutathione (GSH) and histidine (HYS) as effective templates under hydrothermal action. The obtained morphologies revealed interesting structural features, including both cavity-based and flower-shaped structures. The as-synthesised morphologies were noted to actively participate in electro-catalysis of atropine (AT) drug where GSH-assisted structures exhibited the best signal response in terms of current density and over-potential value. The study also discusses the influence of functional groups on the signal sensitivity of atropine electro-oxidation. The functionalisation was carried with the amino acids originally used as effective templates for the growth of Co3O4 nanostructures. The highest increment was obtained when GSH was used as the surface functionalising agent. The GSH-functionalised Co3O4-modified electrode was utilised for the electro-chemical sensing of AT in a concentration range of 0.01 -0.46 mu M. The developed sensor exhibited excellent working linearity (R-2 = 0.999) and signal sensitivity up to 0.001 mu M of AT. The noted high sensitivity of the sensor is associated with the synergy of superb surface architectures and favourable interaction facilitating the electron transfer kinetics for the electro-catalytic oxidation of AT. Significantly, the developed sensor demonstrated excellent working capability when used for AT detection in human urine samples with strong anti-interference potential against common co-existing species, such as glucose, fructose, cysteine, uric acid, dopamine and ascorbic acid. (C) 2016 Elsevier B.V. All rights reserved.

  • 27.
    Ali Soomro, Razium
    et al.
    University of Sindh, Pakistan; University of Bristol, England.
    Nafady, Aynam
    King Saud University, Saudi Arabia; Sohag University, Egypt.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tufail Hussain Sirajuddin; Sherazi, Syed
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ishaq Abro, Muhammad
    Mehran University of Engn and Technology, Pakistan.
    Development of sensitive non-enzymatic glucose sensor using complex nanostructures of cobalt oxide2015In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 34, 373-381 p.Article in journal (Refereed)
    Abstract [en]

    The study reports the synthesis of cobalt oxide (Co3O4) nanostructures and their application in enzyme free electrochemical sensing of glucose. The synthesized nanostructures were elaborately characterized via number of analytical techniques including scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The as-synthesized nanostructures of Co3O4 were found to exhibited nanodisc like morphology with the size dimension in range of 300-500 nm. The obtained morphological features were evaluated for their electrochemical potential towards oxidation of glucose which enabled development of sensitive (27.33 mu A mM(-1) cm(-2)), and stable enzyme free glucose sensor. In addition, the developed sensor showed excellent linearity (r(2)=0.9995), wide detection range (0.5-5.0 mM), lower detection limit (0.8 mu M) and extreme selectivity towards glucose in the presence of common interferents like dopamine (DP), ascorbic acid (AA) and uric acid (UA). The successfully application of developed sensor for real blood glucose analysis further reflects its capability for routine glucose measurement.

  • 28.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Richard Hallam, Keith
    University of Bristol, England.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sirajjuddin,
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    A highly selective and sensitive electrochemical determination of melamine based on succinic acid functionalized copper oxide nanostructures2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 127, 105090-105097 p.Article in journal (Refereed)
    Abstract [en]

    This study presents the development of a highly selective and sensitive electrochemical sensor for the determination of melamine from aqueous environments. The sensor system is based on functionalised marigold-like CuO nanostructures fabricated using a controlled hydrothermal process, where the utilised succinic acid is considered to play a dual role as a functionalising and growth controlling agent (modifier). The fabricated nanostructures exhibit sharp and well-ordered structural features with dimensions (thickness) in the range of 10-50 nm. The sensor system exhibits strong linearity within the concentration range of 0.1 x 10(-9) to 5.6 x 10(-9) M and demonstrates an excellent limit of detection up to 0.1 x 10(-10) M. The extreme selectivity and sensing capability of the developed sensor is attributed to the synergy of selective interaction between succinic acid and melamine moieties, and the high surface area of marigold-like CuO nanostructures. In addition to this, the developed sensor was also utilised for the determination of melamine from real milk samples collected from different regions of Hyderabad, Pakistan. The obtained excellent recoveries proved the feasibility of the sensor for real life applications. The sensor system offers an operative measure for detecting extremely low melamine content with high selectivity in food contents.

  • 29.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Richard Hallam, Keith
    University of Bristol, England.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sanam Sirajjuddin; Memon, Safia
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Amino acid assisted growth of CuO nanostructures and their potential application in electrochemical sensing of organophosphate pesticide2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 190, 972-979 p.Article in journal (Refereed)
    Abstract [en]

    This work reports a highly sensitive electrochemical sensor for organophosphate pesticide (malathion) based on unique and attractive CuO nanostructures. The discussed nanostructures were synthesized using low temperature hydrothermal growth method utilizing green amino acids such as glycine, serine, threonine and histidine as effective bio-compatible templates. The morphological evaluation demonstrated formation of unique and attractive 1-D nanostructures reflecting the effective growth controlling and directing capabilities of the utilized amino acids. The as-synthesized CuO nanostructures were noted to possess high affinity towards malathion which enabled their application as electrode material for the development of affinity based electrochemical sensor. Although, the as-synthesized morphologies were all sensitive towards malathion but the glycine directed triangular flake-like nanostructures exhibited greater sensitivity compared to other competitors. The electrochemical behaviour of the modified electrodes was studied using cyclic voltammetry (CV) whereas, differential pulse voltammetry (DPV) was utilized for the analytical evaluation of the sensor. The developed sensor demonstrated high reproducibility, stability, wide detection window (1-12 nM), and sensitivity to detect malathion up to 0.1 nM based on suppressive signal measurement. In addition, the sensor system exhibited high anti-interference capability in the presence of common co-existing pesticides like lindane, carbendazim, and trichlorfon. The developed sensor provides an effective measure for detecting extremely low concentration of malathion with wide applicability in various fields. (C) 2015 Elsevier Ltd. All rights reserved.

  • 30.
    Ali, Syed M. Usman
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fabrication and characterization of ZnO nanostructures for sensing and photonic device applications2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanotechnology is an emerging inter-disciplinary paradigm which encompasses diverse fields of science and engineering converge at the nanoscale. This nanoscale science and nanostructure engineering have well demonstrated in the fabrication of sensors/transducers devices with faster response time and better sensitivity then the planer version of the sensor’s configurations. Nanotechnology is not just to grow/fabricate nanostructures by just mixing nanoscale materials together but it requires the ability to understand and to precisely manipulate and control of the developed nanomaterials in a useful way. Nanotechnology is aiding to substantially improve, even revolutionize, many technology and industry sectors like information technology, energy, environmental science, medicine/medical instrumentation, homeland security, food safety, and transportation, among many others. Such applications of nanotechnology are delivering in both expected and unexpected ways on nanotechnology’s promise to benefit the society.

    The semiconductor ZnO with wide band gap (~ 3.37 eV) is a distinguish and unique material and its nanostructures have attracted great attention among the researchers due to its peculiar properties such as large exciton binding energy (60 meV) at room temperature, the high electron mobility, high thermal conductivity, good transparency and easiness of fabricating it in the different type of nanostructures. Based on all these fascinating properties, ZnO have been chosen as a suitable material for the fabrication of photonic, transducers/sensors, piezoelectric, transparent and spin electronics devices etc. The objective of the current study is to highlight the recent developments in materials and techniques for electrochemical sensing and hetrostructure light emitting diodes (LEDs) luminescence properties based on the different ZnO nanostructures. The sensor devices fabricated and characterized in the work were applied to determine and monitor the real changes of the chemical or biochemical species. We have successfully demonstrated the application of our fabricated devices as primary transducers/sensors for the determination of extracellular glucose and the glucose inside the human fat cells and frog cells using the potentiometric technique. Moreover, the fabricated ZnO based nanosensors have also been applied for the selective determination of uric acid, urea and metal ions successfully. This thesis relates specifically to zinc oxide nanostructure based electrochemical sensors and photonic device (LED) applications.

    List of papers
    1. A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire
    Open this publication in new window or tab >>A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire
    2010 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 145, no 2, 869-874 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study, a potentiometric glucose biosensor was fabricated by immobilization of glucose oxidase on to zinc oxide nanowires. Zinc oxide nanowires with 250-300 nm diameters and approximately 1.2 mu m lengths were grown on the surface of silver wires with a diameter of 250 mu m. Glucose oxidase (GOD) was electrostatically immobilized on the surface of the well aligned zinc oxide nanowires resulting in sensitive, selective, stable and reproducible glucose biosensors. The potentiometric response vs. Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (0.5-1000 mu M) suitable for intracellular glucose detection. By applying a membrane on the sensor the linear range could be extended to 0.5 mu M to 10 mM, which increased the response time from less than 1 to 4s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents with glucose sensing such as uric acid and ascorbic acid.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keyword
    Glucose oxidase (GOD), Nafion membrane, Potentiometric biosensor, Electrochemical nanodevices, ZnO nanowires, Fast response
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-55508 (URN)10.1016/j.snb.2009.12.072 (DOI)000276589900039 ()
    Available from: 2010-04-30 Created: 2010-04-30 Last updated: 2017-12-12Bibliographically approved
    2. Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate
    Open this publication in new window or tab >>Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate
    2009 (English)In: IEEE Transaction on Nanotechnology, Vol. 8, no 6, 678-683 p.Article in journal (Refereed) Published
    Abstract [en]

    Zinc oxide (ZnO) nanowires were grown on a silver (Ag) wire with a diameter of approximately 250 $mu$m and used in an electrochemical sensor. The enzyme glucose oxidase (GOD) was immobilized on the ZnO nanowires and the silver wire was connected directly to the gate of a MOSFET. Upon exposure to glucose (1-100 $mu$M) the electrochemical response from the glucose oxidase induced a stable measurable voltage change on the gate leading to a strong modulation of the current through the MOSFET. For a sensor with uniform ZnO nanowires functionalized with GOD a fast response time of less than 100 ms, was demonstrated. The effect of the uniformity of the ZnO nanowires on the sensing property was also investigated. The extended gate arrangement facilitated glucose detection in small sample volumes and made it possible to demonstrate the present sensor concept using a standard low threshold MOSFET. The extended gate MOSFET sensor approach demonstrates the possibility and potential of the use of nano-structures coupled to standard electronic components for biosensing applications.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-50566 (URN)10.1109/TNANO.2009.2019958 (DOI)
    Note
    ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Syed M. Usman Ali, Omer Nour, Magnus Willander and Bengt Danielsson, Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate, 2009, IEEE Transaction on Nanotechnology, (8), 6, 678-683. http://dx.doi.org/10.1109/TNANO.2009.2019958 Available from: 2009-10-12 Created: 2009-10-12 Last updated: 2014-01-15
    3. Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
    Open this publication in new window or tab >>Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
    Show others...
    2010 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 25, no 10, 2205-2211 p.Article in journal (Refereed) Published
    Abstract [en]

    In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keyword
    ZnO nanorods; Functionalisation; Intracellular glucose; Electrochemical sensor
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-58381 (URN)10.1016/j.bios.2010.02.025 (DOI)000278702600004 ()
    Note
    Original Publication: Muhammad Asif, Syed Usman Ali, Omer Nour, Magnus Willander, Cecilia Brännmark, Peter Strålfors, Ulrika Englund, Fredrik Elinder and Bengt Danielsson, Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose, 2010, Biosensors & bioelectronics, (25), 10, 2205-2211. http://dx.doi.org/10.1016/j.bios.2010.02.025 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2010-08-13 Created: 2010-08-11 Last updated: 2017-12-12
    4. Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor
    Open this publication in new window or tab >>Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor
    Show others...
    2011 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 11, no 9, 8485-8496 p.Article in journal (Refereed) Published
    Abstract [en]

    This paper presents a prototype wireless remote glucose monitoring system interfaced with a ZnO nanowire arrays-based glucose sensor, glucose oxidase enzyme immobilized onto ZnO nanowires in conjunction with a Nafion (R) membrane coating, which can be effectively applied for the monitoring of glucose levels in diabetics. Global System for Mobile Communications (GSM) services like General Packet Radio Service (GPRS) and Short Message Service (SMS) have been proven to be logical and cost effective methods for gathering data from remote locations. A communication protocol that facilitates remote data collection using SMS has been utilized for monitoring a patients sugar levels. In this study, we demonstrate the remote monitoring of the glucose levels with existing GPRS/GSM network infra-structures using our proposed functionalized ZnO nanowire arrays sensors integrated with standard readily available mobile phones. The data can be used for centralized monitoring and other purposes. Such applications can reduce health care costs and allow caregivers to monitor and support to their patients remotely, especially those located in rural areas.

    Place, publisher, year, edition, pages
    MDPI, 2011
    Keyword
    electrochemical nanosensor, ZnO nanowires, glucose oxidase, Nafion (R) membrane, remote monitoring, data acquisition, Global System for Mobile Communications (GSM)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-71798 (URN)10.3390/s110908485 (DOI)000295211700017 ()
    Available from: 2011-11-04 Created: 2011-11-04 Last updated: 2017-12-08
    5. Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires
    Open this publication in new window or tab >>Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires
    Show others...
    2011 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 152, no 2, 241-247 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study, a potentiometric uric acid biosensor was fabricated by immobilization of uricase onto zinc oxide (ZnO) nanowires. Zinc oxide nanowires with 80-150 nm in diameter and 900 nm to 1.5 mu m in lengths were grown on the surface of a gold coated flexible plastic substrate. Uricase was electrostatically immobilized on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response of the ZnO sensor vs Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (1-650 mu M) suitable for human blood serum. By applying a Nafion (R) membrane on the sensor the linear range could be extended to 1-1000 mu M at the expense of an increased response time from 6.25 s to less than 9 s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2011
    Keyword
    ZnO nanowires, Potentiometric nanosensor, Uricase, Uric acid, Nafion (R), Membrane, Electrochemical nanodevices
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67542 (URN)10.1016/j.snb.2010.12.015 (DOI)000288877700015 ()
    Note
    Original Publication: Syed Usman Ali, Naveed Ul Hassan Alvi, Zafar Hussain Ibupoto, Omer Nur, Magnus Willander and Bengt Danielsson, Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires, 2011, SENSORS AND ACTUATORS B-CHEMICAL, (152), 2, 241-247. http://dx.doi.org/10.1016/j.snb.2010.12.015 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2017-12-11Bibliographically approved
    6. Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes
    Open this publication in new window or tab >>Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes
    Show others...
    2011 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 64, no 8, 697-700 p.Article in journal (Refereed) Published
    Abstract [en]

    White light-emitting diodes (LED) based on ZnO (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN were fabricated and their electrical, optical and electro-optical characteristics were comparatively characterized. All the LED showed rectifying behavior. The nanowalls and nanorods structures have the highest photoluminescence emission intensity in the visible and UV (at 3.29 eV) regions, respectively. The nanowalls have the highest color rendering index, with a value of 95, and the highest electroluminescence intensity with peaks approximately centered at 420, 450 nm and broad peak covering the visible region.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2011
    Keyword
    Zinc oxide, Nanostructure, Aqueous chemical growth, Optical properties, Heterojunctions
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-66849 (URN)10.1016/j.scriptamat.2010.11.046 (DOI)000287908300002 ()
    Available from: 2011-03-22 Created: 2011-03-21 Last updated: 2017-12-11Bibliographically approved
  • 31.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    One-dimensional (1D) nanostructures (NSs) of Zinc Oxide (ZnO) such as nanorods (NRs) have recently attracted considerable research attention due to their potential for the development of optoelectronic devices such as ultraviolet (UV) photodetectors and light-emitting diodes (LEDs). The potential of ZnO NRs in all these applications, however, would require synthesis of high crystal quality ZnO NRs with precise control over the optical and electronic properties. It is known that the optical and electronic properties of ZnO NRs are mostly influenced by the presence of native (intrinsic) and impurities (extrinsic) defects. Therefore, understanding the nature of these intrinsic and extrinsic defects and their spatial distribution is critical for optimizing the optical and electronic properties of ZnO NRs. However, identifying the origin of such defects is a complicated matter, especially for NSs, where the information on anisotropy is usually lost due to the lack of coherent orientation.

    Thus, the aim of this thesis is towards the optimization of the lowtemperature solution-based synthesis of ZnO NRs for device applications. In this connection, we first started with investigating the effect of the precursor solution stirring durations on the deep level defects concentration and their spatial distribution along the ZnO NRs. Then, by choosing the optimal stirring time, we studied the influence of ZnO seeding layer precursor’s types, and its molar ratios on the density of interface defects. The findings of these investigations were used to demonstrate ZnO NRs-based heterojunction LEDs. The ability to tune the point defects along the NRs enabled us further to incorporate cobalt (Co) ions into the ZnO NRs crystal lattice, where these ions could occupy the vacancies or interstitial defects through substitutional or interstitial doping. Following this, high crystal quality vertically welloriented ZnO NRs have been demonstrated by incorporating a small amount of Co into the ZnO crystal lattice. Finally, the influence of Co ions incorporation on the reduction of core-defects (CDs) in ZnO NRs was systematically examined using electron paramagnetic resonance (EPR).

    List of papers
    1. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods
    Open this publication in new window or tab >>Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods
    Show others...
    2015 (English)In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 8, 087180Article in journal (Refereed) Published
    Abstract [en]

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 degrees C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (mu-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

    Place, publisher, year, edition, pages
    AMER INST PHYSICS, 2015
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-122070 (URN)10.1063/1.4929981 (DOI)000360655900089 ()
    Note

    Funding Agencies|Avdanced Functional Materials (AFM) SFO project at Linkoping Univeristy, Sweden

    Available from: 2015-12-18 Created: 2015-10-19 Last updated: 2017-12-01
    2. Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes
    Open this publication in new window or tab >>Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes
    Show others...
    2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 16, 165702- p.Article in journal (Refereed) Published
    Abstract [en]

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5M exhibit stronger yellow emission (similar to 575 nm) compared to those based on 1:1 and 1:3M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination. Published by AIP Publishing.

    Place, publisher, year, edition, pages
    AMER INST PHYSICS, 2016
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-129174 (URN)10.1063/1.4947593 (DOI)000375929900043 ()
    Note

    Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

    Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2017-11-28
    3. Seed layer synthesis effect on the concentration of interface defects and emission spectra of ZnO nanorods/p-GaN light-emitting diode
    Open this publication in new window or tab >>Seed layer synthesis effect on the concentration of interface defects and emission spectra of ZnO nanorods/p-GaN light-emitting diode
    2017 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 214, no 1, 1600333Article in journal (Refereed) Published
    Abstract [en]

    As the low-temperature aqueous chemical synthesis (LT-ACS), holds great promises for the synthesis of one-dimensional (1D) ZnO nanostructure-based light-emitting diodes (LEDs) and hence require parameter tuning for optimal performance. N-ZnO nanorods (NRs)/p-GaN heterojunction LEDs have been synthesized by the LT-ACS using ZnO nanoparticle (NPs) seed layers prepared with different precursor solutions. The effect of these seed layers on the interface defect properties and emission intensity of the as-synthesized n-Zn/p-GaN heterojunction LEDs has been demonstrated by spatially resolved cathodoluminescence (CL) and electroluminescence (EL) measurements, respectively. A significant reduction of the interface defects in the n-ZnO NRs/p-GaN heterostructure synthesized from a seed layer prepared from zinc acetate (ZnAc) with a mixture of potassium hydroxide (KOH) and hexamethylenetetramine (HMTA) (donated as ZKH seed) compared with those prepared from ZnAc and KOH (donated as ZK seed) is observed as revealed by spatially resolved CL. Consequently, the LEDs based on n-ZnO NRs/p-GaN prepared from ZKH seed show an improvement in the yellow emission (approximate to 578nm) compared to that based on the ZK seed as deduced from the electroluminescence measurements. The improvement in the yellow EL emission on the ZKH LED probably attributed to the low presence of the non-radiative defect as deduced by light-output current (L-I) characteristics analysis.

    Place, publisher, year, edition, pages
    WILEY-V C H VERLAG GMBH, 2017
    Keyword
    GaN; interface defects; light-emitting diodes; low-temperature aqueous chemical synthesis; seed layers; ZnO
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-136230 (URN)10.1002/pssa.201600333 (DOI)000394423400006 ()
    Note

    Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials (Faculty Grant SFO-Mat-LiU) at Linkoping University [2009-00971]

    Available from: 2017-03-31 Created: 2017-03-31 Last updated: 2017-11-29
    4. EPR investigation of pure and Co-doped ZnO oriented nanocrystals
    Open this publication in new window or tab >>EPR investigation of pure and Co-doped ZnO oriented nanocrystals
    Show others...
    2017 (English)In: NANOTECHNOLOGY, ISSN 0957-4484, Vol. 28, no 3, 035705Article in journal (Refereed) Published
    Abstract [en]

    Pure and cobalt-doped zinc oxide aligned nanorods have been grown by the low-temperature (90 degrees C) aqueous chemical method on amorphous ZnO seed layer, deposited on a sapphire substrate. High crystallinity of these objects is demonstrated by the electron paramagnetic resonance investigation at liquid helium temperature. The successful incorporation of Co2+ ions in substitution of Zn2+ ones in the ZnO matrix has also been confirmed. A drastic reduction of intrinsic ZnO nanorods core defects is observed in the Co-doped samples, which enhances the structural quality of the NRs. The quantification of substitutional Co2+ ions in the ZnO matrix is achieved by comparison with a reference sample. The findings in this study indicate the potential of using the low-temperature aqueous chemical approach for synthesizing material for spintronics applications.

    Place, publisher, year, edition, pages
    IOP PUBLISHING LTD, 2017
    Keyword
    nanorods; magnetic properties; electron paramagnetic resonance; diluted magnetic semiconductors
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-134300 (URN)10.1088/1361-6528/28/3/035705 (DOI)000391289300001 ()27966469 (PubMedID)
    Note

    Funding Agencies|NATO project [SfP 984735]

    Available from: 2017-02-06 Created: 2017-02-03 Last updated: 2017-10-06
    5. An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods
    Open this publication in new window or tab >>An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods
    Show others...
    2017 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 21, 215102Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g similar to 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zn-i(+)) as CDs and oxygen vacancy (V-O) or oxygen interstitial (O-i) as surface defects. As a result, Co was found to likely occupy the Zn-i(+), leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method. Published by AIP Publishing.

    Place, publisher, year, edition, pages
    AMER INST PHYSICS, 2017
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-138890 (URN)10.1063/1.4984314 (DOI)000402768900026 ()
    Note

    Funding Agencies|NATO [984735]

    Available from: 2017-06-27 Created: 2017-06-27 Last updated: 2017-10-06
    6. Core-defect reduction in ZnO nanorods by cobalt incorporation
    Open this publication in new window or tab >>Core-defect reduction in ZnO nanorods by cobalt incorporation
    Show others...
    2017 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 28, 285705Article in journal (Refereed) Published
    Abstract [en]

    Zinc oxide (ZnO) nanorods grown by the low-temperature (90 degrees C) aqueous chemical method with different cobalt concentration within the synthesis solution (from 0% to 15%), are studied by electron paramagnetic resonance (EPR), just above the liquid helium temperature. The anisotropic spectra of substitutional Co2+ reveal a high crystalline quality and orientation of the NRs, as well as the probable presence of a secondary disordered phase of ZnO: Co. The analysis of the EPR spectra indicates that the disappearance of the paramagnetic native core-defect (CD) at g similar to 1.96 is correlated with the apparition of the Co2+ ions lines, suggesting a gradual neutralization of the former by the latter. We show that only a little amount of cobalt in the synthesis solution (about 0.2%) is necessary to suppress almost all these paramagnetic CDs. This gives insight in the experimentally observed improvement of the crystal quality of diluted ZnO: Co nanorods, as well as into the control of paramagnetic defects in ZnO nanostructures.

    Place, publisher, year, edition, pages
    IOP PUBLISHING LTD, 2017
    Keyword
    nanorods; ZnO; physics defects; electron paramagnetic resonance
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-139388 (URN)10.1088/1361-6528/aa716a (DOI)000404344400005 ()28475103 (PubMedID)
    Note

    Funding Agencies|NATO project Science for Peace (SfP), Novel nanostructures [984735]

    Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2017-10-06
  • 32.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Chey, Chan Oeurn
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods2015In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 8, 087180Article in journal (Refereed)
    Abstract [en]

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 degrees C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (mu-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  • 33.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Iandolo, Donata
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 16, 165702- p.Article in journal (Refereed)
    Abstract [en]

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5M exhibit stronger yellow emission (similar to 575 nm) compared to those based on 1:1 and 1:3M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination. Published by AIP Publishing.

  • 34.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Seed layer synthesis effect on the concentration of interface defects and emission spectra of ZnO nanorods/p-GaN light-emitting diode2017In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 214, no 1, 1600333Article in journal (Refereed)
    Abstract [en]

    As the low-temperature aqueous chemical synthesis (LT-ACS), holds great promises for the synthesis of one-dimensional (1D) ZnO nanostructure-based light-emitting diodes (LEDs) and hence require parameter tuning for optimal performance. N-ZnO nanorods (NRs)/p-GaN heterojunction LEDs have been synthesized by the LT-ACS using ZnO nanoparticle (NPs) seed layers prepared with different precursor solutions. The effect of these seed layers on the interface defect properties and emission intensity of the as-synthesized n-Zn/p-GaN heterojunction LEDs has been demonstrated by spatially resolved cathodoluminescence (CL) and electroluminescence (EL) measurements, respectively. A significant reduction of the interface defects in the n-ZnO NRs/p-GaN heterostructure synthesized from a seed layer prepared from zinc acetate (ZnAc) with a mixture of potassium hydroxide (KOH) and hexamethylenetetramine (HMTA) (donated as ZKH seed) compared with those prepared from ZnAc and KOH (donated as ZK seed) is observed as revealed by spatially resolved CL. Consequently, the LEDs based on n-ZnO NRs/p-GaN prepared from ZKH seed show an improvement in the yellow emission (approximate to 578nm) compared to that based on the ZK seed as deduced from the electroluminescence measurements. The improvement in the yellow EL emission on the ZKH LED probably attributed to the low presence of the non-radiative defect as deduced by light-output current (L-I) characteristics analysis.

  • 35.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Savoyant, Adrien
    Aix Marseille University, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 21, 215102Article in journal (Refereed)
    Abstract [en]

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g similar to 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zn-i(+)) as CDs and oxygen vacancy (V-O) or oxygen interstitial (O-i) as surface defects. As a result, Co was found to likely occupy the Zn-i(+), leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method. Published by AIP Publishing.

  • 36.
    AlSalhi, M S.
    et al.
    King Saud University, Saudi Arabia .
    Atif, M
    King Saud University, Saudi Arabia; National Institute of Laser and Optronics, Nilore, Islamabad, Pakistan.
    Ansari, A A.
    King Saud University, Saudi Arabia .
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. King Saud University, Riyadh, Saudi Arabia.
    Growth and characterization of ZnO nanowires for optical applications2013In: Laser physics, ISSN 1054-660X, E-ISSN 1555-6611, Vol. 23, no 6, 065602Article in journal (Refereed)
    Abstract [en]

    In the present work, cerium oxide CeO2 nanoparticles were synthesized by the sol-gel method and used for the growth of ZnO nanorods. The synthesized nanoparticles were studied by x-ray diffraction (XRD) and Raman spectroscopic techniques. Furthermore, these nanoparticles were used as the seed layer for the growth of ZnO nanorods by following the hydrothermal growth method. The structural study of ZnO nanorods was carried out by means of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and XRD techniques. This study demonstrated that the grown ZnO nanorods are well aligned, uniform, of good crystal quality and have diameters of less than 200 nm. Energy dispersive x-ray (EDX) analysis revealed that the ZnO nanorods are composed only of zinc, cerium as the seed atom, and oxygen atoms, with no other impurities in the grown nanorods. Moreover, a photoluminescence (PL) approach was applied for the optical characterization, and it was observed that the near-band-edge (NBE) emission was the same as that of the zinc acetate seed layer, however the green and orange/red emission peaks were slightly raised due to possibly higher levels of defects in the cerium oxide seeded ZnO nanorods. This study provides an alternative approach for the controlled synthesis of ZnO nanorods using cerium oxide nanoparticles as the seed nucleation layer, improving both the morphology of the nanorods and the performance of devices based upon them.

  • 37.
    Alvi, N H
    et al.
    University of Politecn Madrid, Spain .
    Soto Rodriguez, P E D
    University of Politecn Madrid, Spain .
    Gomez, V J
    University of Politecn Madrid, Spain .
    Kumar, Praveen
    University of Politecn Madrid, Spain .
    Amin, Gul
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Noetzel, R
    University of Politecn Madrid, Spain .
    Highly efficient potentiometric glucose biosensor based on functionalized InN quantum dots2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 15, 153110- p.Article in journal (Refereed)
    Abstract [en]

    We present a fast, highly sensitive, and efficient potentiometric glucose biosensor based on functionalized InN quantum-dots (QDs). The InN QDs are grown by molecular beam epitaxy. The InN QDs are bio-chemically functionalized through physical adsorption of glucose oxidase (GOD). GOD enzyme-coated InN QDs based biosensor exhibits excellent linear glucose concentration dependent electrochemical response against an Ag/AgCl reference electrode over a wide logarithmic glucose concentration range (1 x 10(-5) M to 1 x 10(-2) M) with a high sensitivity of 80mV/decade. It exhibits a fast response time of less than 2 s with good stability and reusability and shows negligible response to common interferents such as ascorbic acid and uric acid. The fabricated biosensor has full potential to be an attractive candidate for blood sugar concentration detection in clinical diagnoses. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758701]

  • 38.
    Alvi, Naveed ul Hassan
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    ul Hasan, Kamran
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The effect of the post-growth annealin g on the color rendering properties of n-Zn Onanorods /p-GaN light emitting diodes2011In: Lighting Research and Technology, ISSN 1477-1535, E-ISSN 1477-0938, Vol. 43, no 3, 331-336 p.Article in journal (Refereed)
    Abstract [en]

    The effect of post-growth annealing on the colour properties of the light emitted by n-ZnO nanorods/p-GaN white LEDs has been investigated. The as-grown ZnO nanorods were annealed in nitrogen, oxygen, argon and air atmospheres at 6008C for 30 minutes. The colour rendering indices and correlated colour temperatures were calculated from the spectra emitted by the LEDs. It was observed that the ambient atmosphere used for annealing is very effective for altering the colour properties of the fabricated LEDs. The LEDs annealed in nitrogen have excellent colour rendering properties with a colour rendering index and a correlated colour temperature of 97 and 2363 K, respectively, in the forward bias and 98 and 3157K in the reverse bias.

  • 39.
    Alvi, N.H.
    et al.
    Universidad Politécnica de Madrid, Spain .
    Soto Rodriguez, P.E. D.
    Universidad Politécnica de Madrid, Spain .
    Kumar, Praveen
    Universidad Politécnica de Madrid, Spain .
    Gomez, V.J.
    Universidad Politécnica de Madrid, Spain .
    Aseev, P.
    Universidad Politécnica de Madrid, Spain .
    Alvi, A.H.
    Government College University, Faisalabad, Pakistan .
    Alvi, M.A.
    Government College University, Faisalabad, Pakistan .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Noetzel, R.
    Universidad Politécnica de Madrid, Spain .
    Photoelectrochemical water splitting and hydrogen generation by a spontaneously formed InGaN nanowall network2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 22, 223104-1-223104-3 p.Article in journal (Refereed)
    Abstract [en]

    We investigate photoelectrochemical water splitting by a spontaneously formed In-rich InGaN nanowall network, combining the material of choice with the advantages of surface texturing for light harvesting by light scattering. The current density for the InGaN-nanowalls-photoelectrode at zero voltage versus the Ag/AgCl reference electrode is 3.4 mA cm(-2) with an incident-photon-to-current-conversion efficiency (IPCE) of 16% under 350 nm laser illumination with 0.075 W.cm(-2) power density. In comparison, the current density for a planar InGaN-layer-photoelectrode is 2 mA cm(-2) with IPCE of 9% at zero voltage versus the Ag/AgCl reference electrode. The H-2 generation rates at zero externally applied voltage versus the Pt counter electrode per illuminated area are 2.8 and 1.61 mu mol.h(-1).cm(-2) for the InGaN nanowalls and InGaN layer, respectively, revealing similar to 57% enhancement for the nanowalls. (C) 2014 AIP Publishing LLC.

  • 40.
    Amin, Gul
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    ZnO and CuO Nanostructures: Low Temperature Growth, Characterization, their Optoelectronic and Sensing Applications2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    One dimensional (1-D), zinc oxide (ZnO) and copper (II) oxide (CuO), nanostructures have great potential for applications in the fields of optoelectronic and sensor devices. Research on nanostructures is a fascinating field that has evolved during the last few years especially after the utilization of the hydrothermal growth method. Using this method variety of nanostructures can be grown from solutions, it is a cheap, easy, and environment friendly approach. These nanostructures can be synthesized on various conventional and nonconventional substrates such as silicon, plastic, fabrics and paper etc.

    The primary purpose of the work presented in this thesis is to realize controllable growth of ZnO, CuO and nanohybrid ZnO/CuO nanostructures and to process and develop white light emitting diodes and sensor devices from the corresponding nanostructures.

    The first part of the thesis deals with ZnO nanostructures grown under different hydrothermal conditions in order to gain a better understanding of the growth. Possible parameters affecting the growth such as the pH, the growth temperature, the growth time, and the precursors  concentration which can alter the morphology of the nanostructures were investigated (paper 1). Utilizing the advantage of the low temperature for growth we synthesized ZnO nanostructures on different substrates, specifically on flexible substrates, which are likely to be integrated with flexible organic substrates for future foldable and disposable electronics (paper 2, 3).

    In the second part of the thesis, using the results and findings from the growth of ZnO nanostructures, it was possible to successfully implement ZnO nanostructures for white light emitting diodes (LEDs) on different flexible substrates (paper 4, 5).

    In paper 4 we realized a ZnO/polymer LED grown on a paper substrate. In paper 5 we extended the idea to print the ZnO nanorods/polymer hybrid LEDs with potential application to large area flexible displays.

    In the last part of the thesis, CuO and nanohybrid ZnO/CuO nanostructures were utilized to fabricate Ag+ detection and humidity sensors. In paper 6 we reported Ag+ selective electrochemical sensor based on the use of functionalized CuO nanopetals. To combine the advantages of both oxides nanostructures and to improve the performance we fabricated a pn-heterojuction using intrinsic n-ZnO nanorods and p-CuO nanostructures which were then utilized as an efficient humidity sensor (paper 7).

    List of papers
    1. Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method
    Open this publication in new window or tab >>Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method
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    2011 (English)In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, no 269692Article in journal (Refereed) Published
    Abstract [en]

    We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C > 400mM) to lower (C < 25mM) C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.

    Place, publisher, year, edition, pages
    NY, USA: Hindawi Publishing Corporation, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-74729 (URN)10.1155/2011/269692 (DOI)000298424100001 ()
    Note
    funding agencies|advanced Functional Material project Sweden||Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2017-12-08Bibliographically approved
    2. Deposition of Well-Aligned ZnO Nanorods at 50 degrees C on Metal, Semiconducting Polymer, and Copper Oxides Substrates and Their Structural and Optical Properties
    Open this publication in new window or tab >>Deposition of Well-Aligned ZnO Nanorods at 50 degrees C on Metal, Semiconducting Polymer, and Copper Oxides Substrates and Their Structural and Optical Properties
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    2010 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 7, 3250-3256 p.Article in journal (Refereed) Published
    Abstract [en]

    A two-step chemical bath deposition was utilized to synthesize ZnO nanorod arrays (ZNRAs) on metals, poly(3,4-ethylenedioxythiophene)/poly(strenesulfonate) (PEDOT/PSS) coated flexible plastic foils, and copper oxides coated glass substrates. The whole synthesis procedure was carried out at a low temperature of 50 degrees C, without any other substrate treatments. The low growth temperature showed improved influence on both the ZNRAs structural and optical properties. Scanning electron microscopy (SEM) images revealed well-aligned ZNRAs with large aspect ratios, and X-ray diffraction (X RI)) analysis indicated that single crystalline ZNRAs were achieved with high c-axial orientation tendency. Room temperature photoluminescence (PL) measurements demonstrated excellent optical properties of the as-grown ZNRAs with very low defect concentration contrary to what was believed to be achieved when lowering the growth temperature. The impact of the low deposition temperature on the ZNRAs structure is discussed in connection to the thermodynamics constraints, while the temperature effect on the defects formation and density in the as-deposited ZNRAs is elaborated and compared with recent theoretical calculations that appeared in the literature.

    Place, publisher, year, edition, pages
    The American Chemical Society, 2010
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-58270 (URN)10.1021/cg100390x (DOI)000279422700059 ()
    Available from: 2010-08-10 Created: 2010-08-09 Last updated: 2017-12-12
    3. Current-transport studies and trap extraction of hydrothermally grown ZnO nanotubes using gold Schottky diode
    Open this publication in new window or tab >>Current-transport studies and trap extraction of hydrothermally grown ZnO nanotubes using gold Schottky diode
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    2010 (English)In: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, ISSN 1862-6300, Vol. 207, no 3, 748-752 p.Article in journal (Refereed) Published
    Abstract [en]

    High-quality zinc oxide (ZnO) nanotubes (NTs) were grown by the hydrothermal technique on n-Si substrate. The room temperature (RT) current-transport mechanisms of Au Schottky diodes fabricated from ZnO NTs and nanorods (NRs) reference samples have been studied and compared. The tunneling mechanisms via deep-level states was found to be the main conduction process at low applied voltage but at the trap-filled limit voltage (V-TFL) all traps were filled and the space-charge-limited current conduction was the dominating current-transport mechanism. The deep-level trap energy and the trap concentration for; the NTs were obtained as similar to 0.27 eV and 2.1 x 10(16) cm(-3), respectively. The same parameters were also extracted for the ZnO NRs The deep-level states observed crossponds to zinc interstitials (Zn-i), which are responsible for the violet emission.

    Place, publisher, year, edition, pages
    WILEY-V C H VERLAG GMBH, PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY, 2010
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-55049 (URN)10.1002/pssa.200925547 (DOI)000276339800054 ()
    Available from: 2010-04-28 Created: 2010-04-28 Last updated: 2014-01-15
    4. ZnO nanorods-polymer hybrid white light emitting diode grown on a disposable paper substrate
    Open this publication in new window or tab >>ZnO nanorods-polymer hybrid white light emitting diode grown on a disposable paper substrate
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    2011 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 5, no 2, 71-73 p.Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate intrinsic white light emission from hybrid light emitting diodes fabricated using an inorganic-organic hybrid junction grown at 50 C on a paper substrate. Cyclotene was first spin coated on the entire substrate to act as a surface barrier layer for water and other nutrient solutions. The active area of the fabricated light emitting diode (LED) consists of zinc oxide nanorods (ZnO NRs) and a poly(9,9-dioctylfluorene) (PFO) conducting polymer layer. The fabricated LED shows clear rectifying behavior and a broad band electroluminescence (EL) peak covering the whole visible spectrum range from 420 nm to 780 nm. The color rendering index (CRI) was calculated to be 94 and the correlated color temperature (CCT) of the LED was 3660 K. The low process temperature and procedure in this work enables the use of paper substrate for the fabrication of low cost ZnO-polymer white LEDs for applications requiring flexible/disposable electronic devices.

    Place, publisher, year, edition, pages
    John Wiley and Sons, Ltd, 2011
    Keyword
    ZnO, PFO, LED, hybrid materials
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67009 (URN)10.1002/pssr.201004446 (DOI)000288178300009 ()
    Available from: 2011-03-25 Created: 2011-03-25 Last updated: 2017-12-11Bibliographically approved
    5. Scale-up synthesis of ZnO nanorods for printing inexpensive ZnO/polymer white light-emitting diode
    Open this publication in new window or tab >>Scale-up synthesis of ZnO nanorods for printing inexpensive ZnO/polymer white light-emitting diode
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    2012 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 47, no 11, 4726-4731 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study, possibilities of scaling up the synthesis of zinc oxide (ZnO) nanorods (NRs) by the hydrothermal method have been explored. It was found that batches yielding several grams can easily be made using common and easily available materials. Further, a printable composition was fabricated by mixing the obtained ZnO NRs into a common solvent-based screen printable varnish. Scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, UV–vis spectroscopy analysis of the scaled up batch indicated that the ZnO nanostructures were of NRs shape, well crystalline and having less defects. Using the ZnO NRs-based printable composition a device fabrication on a flexible substrate was demonstrated, producing a flexible light-emitting device being highly tolerant to bending.

    Place, publisher, year, edition, pages
    Springer, 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-76674 (URN)10.1007/s10853-012-6342-1 (DOI)000302244500026 ()
    Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2017-12-07Bibliographically approved
    6. CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ Measurements
    Open this publication in new window or tab >>CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ Measurements
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    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The electrochemical sensing activity of cupric oxide (CuO) nanopetals was investigated for the detection of silver (I) ions (Ag+. The CuO nanopetals were synthesized on a large area glass substrate by a low-temperature hydrothermal growth process. Structural morphological investigations were carried out using field emission scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction. To check the sensing application of the CuO nanopetals, it was functionalized for selectivity of Ag+. A polymeric membrane with Ag+-selective ionophore was coated on the surface of the CuO nanopetals. CuO nanopetals reveal excellent electrochemical sensing behavior in aqueous solution to selectively detect Ag+. The CuO based sensor exhibits a linear electrochemical response within the concentration range of 1 μM to 100 mM. The functionalized CuO nanopetal based sensor show stable, fast response and high sensitivity for [Ag+]. This work demonstrates a simple technique for sensitive detection of Ag+ and other biochemical species.

    Keyword
    CuO, Nanopetals, Hydrothermal Method, Ag+-Selective Membrane, Electrochemical Sensor
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-76675 (URN)
    Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2017-02-23Bibliographically approved
    7. CuO/ZnO Nanocorals synthesis via hydrothermal technique: growth mechanism and their application as Humidity Sensor
    Open this publication in new window or tab >>CuO/ZnO Nanocorals synthesis via hydrothermal technique: growth mechanism and their application as Humidity Sensor
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    2012 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 23, 11583-11590 p.Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate hydrothermal synthesis of coral-like CuO nanostructures by selective growth on ZnO nanorods (NR) at low temperatures. During the hydrothermal processing the resultant hydroxylated and eroded surface of ZnO NR becomes favorable for the CuO nanostructures growth via oriented attachments. Heterojunction p-n diodes fabricated from the CuO/ZnO nanocorals (NC) reveal stable and high rectification diode properties with a turn-on voltage ~1.52 V and negligible reverse current. The humidity sensing characteristics of the CuO/ZnO NC diodes exhibit a remarkable linear (in a semilogarithmic scale) decrease in the DC resistance by more than three orders when the relative humidity is changed from 30 – 90 %. The NC humidity sensor is also found to reveal the highest sensitivity factor ~6045 among available data for the constituent material’s and a response and recovery time of 6 s and 7 s, respectively.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2012
    Keyword
    Zinc oxide nanorods, copper oxide nanostructures, nanocorals, relative humidity, sensitivity factor
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-76676 (URN)10.1039/c2jm16597j (DOI)000304351400026 ()
    Note
    funding agencies|Swedish government||Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2017-12-07Bibliographically approved
  • 41.
    Amin, Gul
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Asif, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Elsharif Zainelabdin, Ahmed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zaman, Siama
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ Measurements2012In: SENSOR LETTERS, ISSN 1546-198X, Vol. 10, no 3-4, 754-759 p.Article in journal (Refereed)
    Abstract [en]

    The electrochemical sensing activity of cupric oxide (CuO) nanopetals was investigated for the detection of silver (I) ions (Ag+). The CuO nanopetals were synthesized on a large area glass substrate by a low-temperature hydrothermal growth process. Structural morphological investigations were carried out using field emission scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction. To check the sensing application of the CuO nanopetals, it was functionalized for selectivity of Ag+. A polymeric membrane with Ag+-selective ionophore was coated on the surface of the CuO nanopetals. CuO nanopetals reveal excellent electrochemical sensing behavior in aqueous solution to selectively detect Ag+. The CuO based sensor exhibits a linear electrochemical response within the concentration range of 1 mu M to 100 mM. The functionalized CuO nanopetal based sensor show stable, fast response and high sensitivity for [Ag+]. This work demonstrates a simple technique for sensitive detection of Ag+ and other biochemical species.

  • 42.
    Amin, Gul
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Asif, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zainelabdin, Ahmed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zaman, Siama
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ MeasurementsManuscript (preprint) (Other academic)
    Abstract [en]

    The electrochemical sensing activity of cupric oxide (CuO) nanopetals was investigated for the detection of silver (I) ions (Ag+. The CuO nanopetals were synthesized on a large area glass substrate by a low-temperature hydrothermal growth process. Structural morphological investigations were carried out using field emission scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction. To check the sensing application of the CuO nanopetals, it was functionalized for selectivity of Ag+. A polymeric membrane with Ag+-selective ionophore was coated on the surface of the CuO nanopetals. CuO nanopetals reveal excellent electrochemical sensing behavior in aqueous solution to selectively detect Ag+. The CuO based sensor exhibits a linear electrochemical response within the concentration range of 1 μM to 100 mM. The functionalized CuO nanopetal based sensor show stable, fast response and high sensitivity for [Ag+]. This work demonstrates a simple technique for sensitive detection of Ag+ and other biochemical species.

  • 43.
    Amin, Gul
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Asif, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zainelabdin, Ahmed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zaman, Siama
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method2011In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, no 269692Article in journal (Refereed)
    Abstract [en]

    We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C > 400mM) to lower (C < 25mM) C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.

  • 44.
    Amin, Gul
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Sandberg, M. O.
    Acreo AB, Printed Electronics, P.O. Box 787, 60117 Norrköping, Sweden.
    Zainelabdin, Ahmed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zaman, Siama
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Scale-up synthesis of ZnO nanorods for printing inexpensive ZnO/polymer white light-emitting diode2012In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 47, no 11, 4726-4731 p.Article in journal (Refereed)
    Abstract [en]

    In this study, possibilities of scaling up the synthesis of zinc oxide (ZnO) nanorods (NRs) by the hydrothermal method have been explored. It was found that batches yielding several grams can easily be made using common and easily available materials. Further, a printable composition was fabricated by mixing the obtained ZnO NRs into a common solvent-based screen printable varnish. Scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, UV–vis spectroscopy analysis of the scaled up batch indicated that the ZnO nanostructures were of NRs shape, well crystalline and having less defects. Using the ZnO NRs-based printable composition a device fabrication on a flexible substrate was demonstrated, producing a flexible light-emitting device being highly tolerant to bending.

  • 45.
    Andersson Ersman, Peter
    et al.
    Acreo AB, Norrköping, Sweden .
    Kawahara, Jun
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Printed passive matrix addressed electrochromic displays2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 12, 3371-3378 p.Article in journal (Refereed)
    Abstract [en]

    Flexible displays are attracting considerable attention as a visual interface for applications such as in electronic papers and paper electronics. Passive or active matrix-addressing of individual pixels require display elements that include proper signal addressability, which is typically provided by non-linear device characteristics or by incorporating transistors into each pixel, respectively. Including such additional devices into each pixel element make manufacturing of flexible displays using adequate printing techniques very hard or even impossible. Here, we report all-printed passive matrix-addressed electrochromic displays (PMAD) that can be manufactured using standard printing tools. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) serves as the conducting and electrochromic pixel electrodes and carbon paste is used as the pixel counter electrodes. These electrodes sandwich self-assembled layers of a polyelectrolyte that are confined to desired pixel areas via surface energy patterning. The particular choice of materials results in a desired current vs. voltage threshold that enables addressability in electronic cross-point matrices. The resulting PMAD, built up from a robust architecture including only few different materials, operates at less than 3 V, exhibits high color switch contrast without any cross-talk promises for high-volume and low-cost production of flexible displays using reel-to-reel printing tools on plastic foils and on paper.

  • 46.
    Andersson Ersman, Peter
    et al.
    Acreo AB, Sweden.
    Nilsson, David
    creo AB, Sweden.
    Kawahara, Jun
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Acreo AB, Sweden .
    Gustafsson, Göran
    Acreo AB, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fast-switching all-printed organic electrochemical transistors2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 5, 1276-1280 p.Article in journal (Refereed)
    Abstract [en]

    Symmetric and fast (∼5 ms) on-to-off and off-to-on drain current switching characteristics have been obtained in screen printed organic electrochemical transistors (OECTs) including PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)) as the active transistor channel material. Improvement of the drain current switching characteristics is made possible by including a carbon conductor layer on top of PEDOT:PSS at the drain electrode that is in direct contact with both the channel and the electrolyte of the OECT. This carbon conductor layer suppresses the effects from a reduction front that is generated in these PEDOT:PSS-based OECTs. In the off-state of these devices this reduction front slowly migrate laterally into the PEDOT:PSS drain electrode, which make off-to-on switching slow. The OECT including carbon electrodes was manufactured using only standard printing process steps and may pave the way for fully integrated organic electronic systems that operate at low voltages for applications such as logic circuits, sensors and active matrix addressed displays.

  • 47.
    Andrijauskas, T.
    et al.
    Vilnius State University.
    Shylau, Artsem
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Thomas-Fermi and Poisson modeling of gate electrostatics in graphene nanoribbon2012In: Lithuanian Journal of Physics, ISSN 1648-8504, Vol. 52, no 1, 63-69 p.Article in journal (Refereed)
    Abstract [en]

    We describe a simple graphene nanoribbon and bottom gate system and present numerical algorithms for solving Poissons and Thomas-Fermi equations for electrons in the graphene nanoribbon. The Poissons equation is solved using finite difference and finite element methods. Using the Poisson and Thomas-Fermi equations we calculate an electrostatic potential and surface electron density in the graphene nanoribbon. Finally, the Poisson-Thomas-Fermi model for the graphene nanoribbon is compared to a tight-binding Hartree model. The results show a good correspondence with the tight-binding model. The developed solver of the Poissons equation can be used in the future calculations of more complex graphene and gate systems.

  • 48.
    Anton, Gagner
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hebib, Nino
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    FPGA Software Development for Control Purposes of High-Frequency Switching Power Converters2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    FPGA stands for Field Programmable Gate Array and it is a technology that has been on the rise the last decades. With a decrease in size of the logic elements commercially available products have started to have more built-in functionality in one package and by being reprogrammable makes the system a powerful competitor among its neighbors. FPGA technology in comparison with Digital Signal Processing technology is generally interesting because of the parallelism of the programming that can be made. This allows for more operations in less time. In this thesis a system is developed to control power converters with control signals in high frequency. A previous project is used as a base and a toolchain of new components are implemented to create a new, more generic system. The previous system is evaluated and a new protocol for communication is developed. The toolchain with the necessary control blocks is implemented in Quartus II that includes a timer block, a pulse width modulation block, a PID controller block and a FIR-filter block. The system is used to control a power converter and the result is evaluated.

  • 49.
    Apaydin, Dogukan H.
    et al.
    Johannes Kepler University of Linz, Austria.
    Gora, Monika
    University of Warsaw, Poland.
    Portenkirchner, Engelbert
    University of Innsbruck, Austria.
    Oppelt, Kerstin T.
    Johannes Kepler University of Linz, Austria.
    Neugebauer, Helmut
    Johannes Kepler University of Linz, Austria.
    Jakesoya, Marie
    Johannes Kepler University of Linz, Austria.
    Glowacki, Eric D.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Kunze-Liebhaeuser, Julia
    University of Innsbruck, Austria.
    Zagorska, Malgorzata
    Warsaw University of Technology, Poland.
    Mieczkowski, Jozef
    University of Warsaw, Poland.
    Serdar Sariciftci, Niyazi
    Johannes Kepler University of Linz, Austria.
    Electrochemical Capture and Release of CO2 in Aqueous Electrolytes Using an Organic Semiconductor Electrode2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 15, 12919-12923 p.Article in journal (Refereed)
    Abstract [en]

    Developing efficient methods for capture and controlled release of carbon dioxide is crucial to any carbon. capture and utilization technology. Herein we present an approach using an organic. semiconductor electrode to electrochemically capture dissolved CO2 in aqueous electrolytes. The process relies on electrochemical reduction of a thin film of a naphthalene bisimide derivative, 2,7,bis (4-(2- (2-ethylhexyl)thiazol-4-yl)phenyObenzo [lmn][3,8] phenanthroline-1,3,6,8(2H,7H)-tetraone (NBIT). This molecule is specifically tailored to afford one-electron reversible and one-electron quasi-reversible reduction in aqueous conditions while, not dissolving or degrading. The reduced NBIT reacts with CO2 to form a stable aemicarbonate salt, which can be subsequently oxidized electrochemically to release CO2. The semicarbonate structure is confirmed by in situ IR spectroelectrochemistry. This process of capturing and releasing carbon dioxide can be realized in an oxygen-free environment under ambient pressure and temperature, with uptake efficiency for CO2 capture of similar to 2.3 mmol g(-1). This is on par with the best solution-phase amine chemical capture technologies available today.

  • 50.
    Arain, Munazza
    et al.
    University of Sindh, Pakistan.
    Nafady, Ayman
    King Saud University, Saudi Arabia; Sohag University, Egypt.
    Sirajuddin,
    Univ Sindh, Pakistan.
    Ibupoto, ZH
    Univ Sindh, Pakistan.
    Sherazi, Syed Tufail Hussain
    University of Sindh, Pakistan.
    Shaikh, Tayyaba
    University of Sindh, Pakistan.
    Khan, Hamayun
    Islamia Coll University, Pakistan.
    Alsalme, Ali
    King Saud University, Saudi Arabia.
    Niaz, Abdul
    Bannu University of Science and Technology, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Simpler and highly sensitive enzyme-free sensing of urea via NiO nanostructures modified electrode2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 45, 39001-39006 p.Article in journal (Refereed)
    Abstract [en]

    In this study, NiO nanostructures were synthesized via a hydrothermal process using ascorbic acid as doping agent in the presence of ammonia. As prepared nanostructures were characterized using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area analysis, and thermogravimetric analysis (TGA). These analyses showed that these nanostructures are in the form of cotton-like porous material and crystalline in nature. Furthermore, the average size of these NiO crystallites was estimated to be 3.8 nm. These nanostructures were investigated for their potential to be a highly sensitive and selective enzyme-free sensor for detection of urea after immobilizing on a glassy carbon electrode (GCE) using 0.1% Nafion as binder. The response of this as developed amperometric sensor was linear in the range of 100-1100 mu M urea with a R-2 value of 0.990 and limit of detection (LOD) of 10 mu M. The sensor responded negligibly to various interfering species including glucose, uric acid, and ascorbic acid. This sensor was applied successfully for determining urea in real water samples such as mineral water, tap water, and river water with acceptable recovery.

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