liu.seSearch for publications in DiVA
Change search
Refine search result
23456 201 - 250 of 276
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Efficient and Stable Co3O4/ZnO Nanocomposite for Photochemical Water Splitting2022In: Journal of cluster science, ISSN 1040-7278, E-ISSN 1572-8862, Vol. 33, no 1, p. 387-394Article in journal (Refereed)
    Abstract [en]

    In this study, an efficient Co3O4/ZnO based composite was prepared by the low temperature aqueous chemical growth method for photoelectrochemical water splitting. Both ZnO and Co3O4 constituents are identified in the composite sample through X-ray diffraction technique. Scanning electron microscopy has shown the nanorod like morphology of ZnO with etched top surface. The energy dispersive spectroscopy has shown the presence of cobalt, oxygen and zinc as the main elements in the composite samples. The Co3O4/ZnO composite (with low content of cobalt chloride hexahydrate) shows a significant increase in the photocurrent density (3 mA/cm(2) at 0.5 V vs Ag/AgCl, which is 10 times higher than the pristine ZnO). Importantly, a fast and stable photocurrent response is found at an illumination of 1 Sun of light. The superior performance of the Co3O4/ZnO composite system is attributed to the facile promotion of electron-hole charge carrier separation and favourable charge transport. Furthermore, the electrochemical impedance spectroscopy showed a small charge transfer resistance of 259.30 Ohms for the composite material and consequently a robust water splitting is obtained. The prepared composite is earth abundant, inexpensive and scalable, therefore it can be used for diverse applications.

  • 202.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media2019In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 11, p. 2879-2887Article in journal (Refereed)
    Abstract [en]

    Developing highly active nonprecious metal and binder free bifunctional electrocatalysts for water splitting is a challenging task. In this study, we used a simple strategy to deposit a nickel iron layered double hydroxide (NiFeLDH) onto cobalt oxide (Co3O4) nanowires. The cobalt oxide nanowires are covered with thin nanosheets of NiFeLDH forming a core shell structure. The Co3O4 nanowires contain the mixed oxidation states of Co2+ and Co3+, and the surface modification of Co3O4 nanowires has shown synergetic effects due to there being more oxygen defects, catalytic sites, and enhanced electronic conductivity. Further, the core shell structure of Co3O4 nanowires demonstrated a bifunctional activity for water splitting in 1 M KOH aqueous solution. From the hydrogen evolution reaction (HER), a current density of 10 mA cm - 2 is achieved at a potential of - 0.303 V vs. reversible hydrogen electrode (RHE). Meanwhile for the case of the oxygen evolution reaction (OER), a current density of 40 mA cm - 2 is measured at a potential of 1.49 V vs. RHE. Also, this electrocatalyst has shown a considerable long- term stability of 15 h for both the HER and the OER. Importantly, electrochemical impedance spectroscopy has shown that the NiFeLDH integration onto cobalt oxide exhibited around 3 fold decrease of charge transfer resistance for both the HER and the OER in comparison with pristine cobalt oxide films, which reveals an excellent electrocatalytic activity for both faradaic processes. All these results confirm that the proposed electrocatalyst can be integrated into an efficient water splitting system.

    Download full text (pdf)
    fulltext
  • 203.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media2019In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 44, no 48, p. 26148-26157Article in journal (Refereed)
    Abstract [en]

    In this study, we incorporate a copper impurity into (Co3O4) nanowires precursor that turn them into an active catalyst for the hydrogen evolution reaction in 1M KOH. The XRD and XPS results are in good agreement and confirmed the formation of Co3O4-CuO nano composite by wet chemical method. To date, the performance of hydrogen evolution reaction in alkaline for the composite catalyst is comparable or superior to cobalt oxide based HER electro-catalysts. The HER catalyst exhibits the lowest Tafel slope of 65 mVdec(-1) for the cobalt-based catalysts in alkaline media. A current density of 10 mA/cm(2) is achieved at a potential of 0.288 V vs reversible hydrogen electrode (RHE). The mixed transition metal oxide Co3O4-CuO based HER electro-catalyst is highly stable and durable. The EIS results demonstrates that HER is highly favorable on the Co3O4-CuO due to the relatively small charge transfer resistance (173.20 Ohm) and higher capacitance values (1.97 mF). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

    Download full text (pdf)
    fulltext
  • 204.
    ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Asif, Muhammad H.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sandberg, Mats O.
    Acreo AB, Norrköping, Sweden.
    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.
    Fagerholm, Siri
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Graphene-based Biosensor for Intracellular Glucose MeasurementsManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we report a novel graphene-based glucose micro sensor for measuring intracellular glucose. A borosilicate glass capillary (0.7 um diameter) is coated first with a graphene ink and then with a graphene-enzyme conjugate. The functional groups, presumably on the edge plane of graphene, assist binding with the free amine terminals of the glucose oxidase enzyme to result in a better immobilization. The as-prepared graphene biosensor exhibits a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference is linear over the concentration range of interest (10–1000μM). The measured glucose concentration in human adipocytes by using our graphene based sensor is consistent with reported values of glucose concentration. This device demonstrates a simple technique to measure intracellular glucose concentration.

  • 205.
    ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. CESAT, Islamabad, Pakistan.
    Asif, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. COMSATS Institute Informat Technology, Lahore, Pakistan.
    Umair Hassan, Muhammad
    COMSATS Institute Informat Technology, Lahore, Pakistan.
    Sandberg, Mats O.
    Acreo AB, Norrköping, Sweden.
    Nour, Omer
    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.
    Fagerholm, Siri
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    A Miniature Graphene-based Biosensor for Intracellular Glucose Measurements2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 174, p. 574-580Article in journal (Refereed)
    Abstract [en]

    We report on a small and simple graphene-based potentiometric sensor for the measurement of intracellular glucose concentration. A fine borosilicate glass capillary coated with graphene and subsequently immobilized with glucose oxidase (GOD) enzyme is inserted into the intracellular environment of a single human cell. The functional groups on the edge plane of graphene assist the attachment with the free amine terminals of GOD enzyme, resulting in a better immobilization. The sensor exhibits a glucose-dependent electrochemical potential against an Ag/AgCl reference microelectrode which is linear across the whole concentration range of interest (10 - 1000 mu M). Glucose concentration in human fat cell measured by our graphene-based sensor is in good agreement with nuclear magnetic resonance (NMR) spectroscopy.

  • 206.
    ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Magnusson, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Controlled Growth of ZnO Nanowires on Graphene surfaceManuscript (preprint) (Other academic)
    Abstract [en]

    Graphene, a perfect two-dimensional (2D) and completely p-conjugated honeycomb network of carbon, can potentially be a platform to serve as a substrate for growth of semiconductor nanostructures. High quality graphene films are prepared by sublimation on semiinsulating SiC grown by high temperature chemical vapor deposition (HTCVD) and on SiO2 by wet chemistry routine. Selective growth of ZnO nanowires (NWs) is performed on the graphene surface by the hydrothermal method. Mechanical stability of the graphene-ZnO heterojunction is tested by a utilizing a very simple technique. 1D ZnO NWs exhibit strong binding with 2D graphene surface and the NWs grown on graphene are of high crystal quality. This result can be very important for realizing the ultimate goal of 3D assembly at the nanoscale. The electrical contact between graphene and ZnO was analyzed by current vs. voltage (I-V) characteristics. The graphene-ZnO junction behaved as a typical metal-semiconductor ohmic contact lacking a contact barrier. These combined graphene-ZnO 3D heterojunction can pave the way for the next-generation of nano and optoelectronic devices.

  • 207.
    ul Hasan, Kamran
    et al.
    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.
    Screen printed ZnO UV photoconductive sensor on pencil drawn circuitry over paper2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 21, p. 211104-Article in journal (Refereed)
    Abstract [en]

    Many applications require a low-cost and large-scale mode of flexible electronics with reasonably high photoresponse that can be detected without high precision measurement systems. We demonstrate a very easy to fabricate ZnO UV sensor, made on common pencil drawn circuit over a paper. ZnO nanocrystals were extracted in a high throughput via a simple and green route. This sensor is well capable of detecting UV light and demonstrates features comparable to those of made with complex and expensive techniques.

    Download full text (pdf)
    fulltext
  • 208.
    Ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sandberg, Mats O
    Acreo AB.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Polycation stabilization of graphene suspensions2011In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6, no 493Article in journal (Refereed)
    Abstract [en]

    Graphene is a leading contender for the next-generation electronic devices. We report a method to produce graphene membranes in the solution phase using polymeric imidazolium salts as a transferring medium. Graphene membranes were reduced from graphene oxides by hydrazine in the presence of the polyelectrolyte which is found to be a stable and homogeneous dispersion for the resulting graphene in the aqueous solution. A simple device with gold contacts on both sides was fabricated in order to observe the electronic properties.

    Download full text (pdf)
    fulltext
  • 209.
    Ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Centres of Excellence in Science & Applied Technologies (CESAT), Islamabad, Pakistan.
    Sandberg, Mats O.
    Acreo AB, Norrköping, Sweden.
    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.
    ZnO/Polyfluorene Hybrid LED on an Efficient Hole-Transport Layer of Graphene Oxide and Transparent Graphene Electrode2014In: Advanced Optical Materials, ISSN 2195-1071, Vol. 2, no 4, p. 326-330Article in journal (Refereed)
    Abstract [en]

    A novel Inorganic/organic hybrid light emitting diodes (LEDs) have been fabricated using reduced graphene oxide (rGO) films as a transparent conductive electrode and graphene oxide (GO) as a hole transporting layer (HTL). ZnO nanowires (NWs) are obtained by low temperature solution-based procedure. The whole device is fabricated through simple approach of spin coating and screen printing. The results indicate that graphene can be a simple solution processable substitute for PEDOT: PSS as the effective hole transport (electron blocking) layer and the ITO as a transparent conductive electrode in optoelectronic devices.

  • 210.
    Ul Hasan, Kamran
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ul Hassan Alvi, Naveed
    Linköping University, Department of Science and Technology. 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.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Single nanowire-based UV photodetectors for fast switching2011In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6, no 348Article in journal (Refereed)
    Abstract [en]

    Relatively long (30 mu m) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

    Download full text (pdf)
    fulltext
  • 211.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Riaz, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tzamalis, G
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Junction temperature in n-ZnO nanorods/(p-4H-SiC, p-GaN, and p-Si) heterojunction light emitting diodes2010In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 54, no 5, p. 536-540Article in journal (Refereed)
    Abstract [en]

    The junction temperature of n-ZnO nanorods/(p-4H-SiC, p-GaN, and p-Si) heterojunction light emitting diodes (LEDs) at built-in potential was modeled and experiments were performed at various temperatures (15-65 degrees C) to validate the model. As the LEDs operate near the built-in potential thats why it is interesting to investigate the temperature coefficient of forward voltage near the built-in potential (similar to V-o). The model and experimental values of the temperature coefficient of forward voltage near the built-in potential (similar to V-o) were compared. We measured the experimental temperature coefficient of the series resistance. By including the temperature coefficient of the series resistance in the model, the theoretical and experimental values become very close to each other. It was found that the series resistance has the main contribution in the junction temperature of our devices. We also measured the junction temperature above the built-in potential and found that the model deviates at higher forward voltage. From this observation we concluded that the model is applicable for low power devices, operated near the built-in potential.

  • 212.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ul Hasan, Kamran
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes2011In: NANOSCALE RESEARCH LETTERS, ISSN 1931-7573, Vol. 6, no 1, p. 130-Article in journal (Refereed)
    Abstract [en]

    In this article, the electroluminescence (EL) spectra of zinc oxide (ZnO) nanotubes/p-GaN light emitting diodes (LEDs) annealed in different ambients (argon, air, oxygen, and nitrogen) have been investigated. The ZnO nanotubes by aqueous chemical growth (ACG) technique on p-GaN substrates were obtained. The as-grown ZnO nanotubes were annealed in different ambients at 600 degrees C for 30 min. The EL investigations showed that air, oxygen, and nitrogen annealing ambients have strongly affected the deep level emission bands in ZnO. It was concluded from the EL investigation that more than one deep level defect is involved in the red emission appearing between 620 and 750 nm and that the red emission in ZnO can be attributed to oxygen interstitials (O-i) appearing in the range from 620 nm (1.99 eV) to 690 nm (1.79 eV), and to oxygen vacancies (V-o) appearing in the range from 690 nm (1.79 eV) to 750 nm (1.65 eV). The annealing ambients, especially the nitrogen ambient, were also found to greatly influence the color-rendering properties and increase the CRI of the as - grown LEDs from 87 to 96.

    Download full text (pdf)
    fulltext
  • 213.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    ul Hassan, Wasied
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Farooq, B
    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.
    Influence of different growth environments on the luminescence properties of ZnO nanorods grown by the vapor-liquid-solid (VLS) method2013In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 106, p. 158-163Article in journal (Refereed)
    Abstract [en]

    ZnO nanorods (NRs) are grown in different atmospheres (argon, air, oxygen and nitrogen) by using the vapor-liquid-solid (VLS) method. The influence of different growth atmospheres on the luminescence properties has been investigated by using the photoluminescence (PL), cathodoluminescence (CL) and electroluminescence (EL) spectra measurements at room temperature. The PL spectra investigations reveal that the air, the oxygen and the nitrogen growth atmospheres have strongly affected the oxygen interstitial (O-i) and oxygen vacancy (V-o) related deep level emission (DLE) bands in ZnO and this fact is also found consistent with the cathodoluminescence (CL) and electroluminescence (EL) spectra investigations. The color rendering investigations reveal that the growth atmospheres have also influenced the color quality of the emitted light. These results indicate that the defects related emissions from the band gap of ZnO NRs can be tuned by using different growth atmospheres. These results can be useful for the development of white light emitting diodes (WLEDs).

  • 214.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, S
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes2011In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 64, no 8, p. 697-700Article in journal (Refereed)
    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.

  • 215.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The effect of the post-growth annealing on the electroluminescence properties of n-ZnO nanorods/p-GaN light emitting diodes2010In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 47, no 6, p. 754-761Article in journal (Refereed)
    Abstract [en]

    In this paper we investigated the effect of post-growth annealing treatment on the electroluminescence (EL) of n-ZnO nanorods/p-GaN light emitting diodes. The ZnO nanorods were grown by the low temperature (less than100 degrees C) aqueous chemical growth (ACC) technique. The as-grown ZnO nanorods were annealed in nitrogen, oxygen, argon, and air ambients at 600 degrees C for 30 min. The electroluminescence (EL) measurements showed that the deep level defects related emissions in ZnO were greatly affected by the annealing of the n-ZnO nanorods in different ambients. By comparing the EL spectra of ZnO nanorods annealed in different ambients it was found that nitrogen annealing ambient is very effective in shifting the emission peak from the green region to the red region. It was also concluded that the red emission in ZnO was attributed to oxygen vacancies WO. The effect of the annealing ambient and the temperature dependence electroluminescence were discussed with relation to the intrinsic and extrinsic defects.

  • 216.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Aijazi, Tasuif
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Axelsson, Kent
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor2011In: Sensors, E-ISSN 1424-8220, Vol. 11, no 9, p. 8485-8496Article in journal (Refereed)
    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.

    Download full text (pdf)
    fulltext
  • 217.
    Usman Ali, Syed
    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. Pakistan.
    Fulati, Alimujiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Brännmark, Cecilia
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Englund, Ulrika
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Elinder, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Danielsson, Bengt
    Lund University.
    Intracellular K(+) Determination With a Potentiometric Microelectrode Based on ZnO Nanowires2011In: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 10, no 4, p. 913-919Article in journal (Refereed)
    Abstract [en]

    The fabrication and application of an intracellular K(+)-selective microelectrode is demonstrated. ZnO nanowires with a diameter of 100-180 nm and a length of approximately 1.5. m are grown on a borosilicate glass microcapillary. The ZnO nanowires were coated by a K(+)-ionophore-containing membrane. The K(+)-selective microelectrode exhibited a K(+)-dependent potentiometric response versus an Ag/AgCl reference microelectrode that was linear over a large concentration range (25 . M-125 mM) with a minimum detection limit of 1 . M. The measured K(+) concentrations in human adipocytes and in frog oocytes were consistent with values of K(+) concentrations reported in the literature. The sensor has several advantages including ease of fabrication, ease of insertion into the cells, low cost, and high selectivity features that make this type of sensor suitable to characterize physiologically relevant ions within single living cells.

    Download full text (pdf)
    fulltext
  • 218.
    Usman Ali, Syed
    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.
    Salman, Salah
    Acromed Invest AB, SE-22643 Lund, Sweden .
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Acromed Invest AB.
    Selective determination of urea using urease immobilized on ZnO nanowires2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 160, no 1, p. 637-643Article in journal (Refereed)
    Abstract [en]

    Well-aligned zinc oxide (ZnO) nanowire arrays were fabricated on gold-coated plastic substrates using a low-temperature aqueous chemical growth (ACG) method. The ZnO nanowire arrays with 50-130 nm diameters and similar to 1 mu m in lengths were used in an enzyme-based urea sensor through immobilization of the enzyme urease that was found to be sensitive to urea concentrations from 0.1 mM to 100 mM. Two linear sensitivity regions were observed when the electrochemical responses (EMF) of the sensors were plotted vs. the logarithmic concentration range of urea from 0.1 mM to 100 mM. The proposed sensor showed a sensitivity of 52.8 mV/decade for 0.1-40 mM urea and a fast response time less than 4s was achieved with good selectivity, reproducibility and negligible response to common interferents such as ascorbic acid and uric acid, glucose. K(+) and Na(+) ions.

    Download full text (pdf)
    fulltext
  • 219.
    Usman Ali, Syed M
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, B.
    Lund University.
    A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire2010In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 145, no 2, p. 869-874Article in journal (Refereed)
    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.

  • 220.
    Usman Ali, Syed M.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Lund University.
    Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate2009In: IEEE Transaction on Nanotechnology, Vol. 8, no 6, p. 678-683Article in journal (Refereed)
    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.

    Download full text (pdf)
    FULLTEXT01
  • 221.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ul Hassan Alvi, Naveed
    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.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Acromed Invest AB.
    Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 152, no 2, p. 241-247Article in journal (Refereed)
    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.

    Download full text (pdf)
    FULLTEXT01
  • 222.
    Wadeasa, Amal
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Beegum, S L
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Raja, S
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The demonstration of hybrid n-ZnO nanorod/p-polymer heterojunction light emitting diodes on glass substrates2009In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 95, no 3, p. 807-812Article in journal (Refereed)
    Abstract [en]

    We report a demonstration of heterojunction light emitting diode (LED) based on a hybrid n-ZnO-nanorod/p-polymer layered structure. The ZnO was grown using the aqueous chemical growth (ACG) on top of the polymer(s) which were deposited on glass. The current-voltage (I-V) behavior of the heterojunctions showed good rectifying diode characteristics. Room-temperature electroluminescence (EL) spectra of the LEDs provided a broad emission band over a wide LED color range (430-650 nm), in which both zinc and oxygen vacancy peaks are clearly detected. We present here luminescent devices based on the use of ZnO-nanorods in combination with two different blended and multi-layered p-type polymers. Electroluminescence of the first batch of devices showed that white bluish strong emission for the presently used polymers is clearly observed. We obtained a turn-on voltage of 3 V and break-down voltage equal to -6 V for PVK-TFB blended device. The corresponding values for the NPD-PFO multilayer device were 4 V and -14 V, respectively. The rectification factors were equal to 3 and 10 for the two devices, respectively. The films and devices processed were characterized by scanning electron microscopy (SEM), DEKTAK 3ST Surface Profile, Semiconductor Parameter Analyzer, photoluminescence (PL), and electroluminescence (EL).

  • 223.
    Wadeasa, Amal
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tzamalis, G.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Solution processed ZnO nanorods/polyfluorene semiconductor heterojunctions with white light photoluminescenceManuscript (preprint) (Other academic)
    Abstract [en]

    Hybrid inorganic-organic semiconductor heterojunctions are nowadays scrutinized for optoelectronic devices, such as solar cells and light emitting diodes. Here, ZnOnanorods/ polyfluorene heterojunctions have been entirely fabricated from solution by wet chemistry and low temperature processes. The morphology of the polyfluorene film appears to be an important parameter to control the growth of the ZnO nanorods and affects their optical properties. The visible emission of the conjugated polymer and the ZnO are complementary and provide a broad emission in the visible. Because of its solution processability and broad emission, the ZnO/polyfluorene heterojunction is promising for large area white lightning applications.

  • 224.
    Wadeasa, Amal
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tzamalis, G
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sehati, Parisa
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Solution processed ZnO nanowires/polyfluorene heterojunctions for large area lightening2010In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 490, no 4-6, p. 200-204Article in journal (Refereed)
    Abstract [en]

    Hybrid inorganic-organic semiconductor heterojunctions are nowadays scrutinized for optoelectronic devices, such as solar cells and light emitting diodes. Here, ZnO nanowires/polyfluorene heterojunctions have been entirely fabricated from solution by wet chemistry and low temperature processes. The transparent plastic electrode PEDOT injects holes in the polyfluorene, while the electrons are injected via the ZnO-Au contact, thus avoiding the use of air sensitive low work function metals. The hybrid inorganic-organic light emitting diode emits almost white light. Because of its solution processability, stable cathode, low cost and low temperature process, the ZnO/polymer heterojunction devices are promising for large area lightening applications.

  • 225.
    Wadesa, Amal
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander , Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The effect of the interlayer design on the electroluminescence and electrical properties of n-ZnO nanorod/p-type blended polymer hybrid light emitting diodes2009In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, no 6, p. 065710-Article in journal (Refereed)
    Abstract [en]

    Hybrid light emitting diodes (LEDs) based on n-ZnO nanorods and blended polymers were fabricated and characterized. The blended polymers consisted of a blue emitting polymer and a charge transport polymer. The effect of the interlayer design on the electrical and electroluminescent characteristics of these hybrid LEDs was investigated. We demonstrated that by adding a calcium (2) acetylacetonate [Ca(acac)(2)] layer between the blended polymer layer and the ZnO nanorods, an increase in device performance was observed. The purpose of the extra layer was to act as a band offset stepping layer (offset divider). Moreover, the effect of the stepper layer thickness for this offset stepping layer was studied. The results indicate that LED performance is greatly affected by the presence and thickness of this band offset stepping layer.

    Download full text (pdf)
    FULLTEXT01
  • 226.
    Wahab, H. A.
    et al.
    NRC, Egypt.
    Salama, A. A.
    El Azhar Univ, Egypt.
    El Saeid, A. A.
    El Azhar Univ, Egypt.
    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.
    Battisha, I. K.
    NRC, Egypt.
    Zinc oxide nano-rods based glucose biosensor devices fabrication2018In: RESULTS IN PHYSICS, ISSN 2211-3797, Vol. 9, p. 809-814Article in journal (Refereed)
    Abstract [en]

    ZnO is distinguished multifunctional material that has wide applications in biochemical sensor devices. For extracellular measurements, Zinc oxide nano-rods will be deposited on conducting plastic substrate with annealing temperature 150 degrees C (ZNRP150) and silver wire with annealing temperature 250 degrees C (ZN(R)W250), for the extracellular glucose concentration determination with functionalized ZN(R)-coated biosensors. It was performed in phosphate buffer saline (PBS) over the range from 1 mu M to 10 mM and on human blood plasma. The prepared samples crystal structure and surface morphologies were characterized by XRD and field emission scanning electron microscope FESEM respectively. (C) 2018 The Authors. Published by Elsevier B.V.

    Download full text (pdf)
    dataset
  • 227.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ali Abbasi, Mazhar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, K.
    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.
    Hussain Ibupoto, Zafar
    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.
    UV detectors and LEDs in different metal oxide nanostructures2014Conference paper (Refereed)
    Abstract [en]

    Different composite nanostructures based pn-junctions have been synthesized using the low temperature hydrothermal chemical growth. The composite nanostructures based pn junctions demonstrated here include p-NiO/n-ZnO, p-CuO/n-ZnO, and p-NiO/n-TiO2. Structural characterization of these composite nanostructures based pn-junctions was performed by different complementary tools and the results indicated that reasonable device quality crystals have been achieved. His act was also confirmed by the rectifying electrical behavior observed from these junctions. Further, the different composite nanostructures based junctions were used to demonstrate UV detectors and visible light emitting diodes (LEDs) operating with acceptable performance.

  • 228.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Elhag, Sami
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Nour, Eiman
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Comparison between different metal oxide nanostructures and nanocomposites for sensing, energy generation and energy harvesting2016In: OXIDE-BASED MATERIALS AND DEVICES VII, SPIE-INT SOC OPTICAL ENGINEERING , 2016, Vol. 9749, no UNSP 97491LConference paper (Refereed)
    Abstract [en]

    Highlights from research on different nanocomposites and nanostructures for sensing and other energy related applications will be presented. The synthesized nanostructures and nanocomposites presented here were all obtained using the low temperature (amp;lt; 100 degrees C) chemical approach. Nanostructures featured by small foot-print and synthesized by the low temperature aqueous chemical approach allows the utilization of non-conventional solid and soft substrates like e.g. glass, plastic, textile and paper. We here present results from different metal oxide nanostructures employed for chemical sensing and some innovative energy related applications. Efficient sensitive and selective sensing of dopamine, melamine, and glucose are presented as some examples of self-powered sensors utilizing the electrochemical phenomenon i.e. transferring chemical energy into electrical signal. Further the use of nanomaterials for developing self-powered devices utilizing mechanical ambient energy is presented via piezoelectric and triboelectric effects. Here the self-powered devices and systems were relying on utilizing the electormechanical phenomenon i.e. transferring ambient mechanical energy into useful electrical energy. Finally the visibility of nanomaterials prepared by the low temperature chemical synthesis as possible low cost replacement of Pt electrodes for hydrogen production is briefly presented and discussed.

  • 229.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Savoyant, A.
    Aix Marseille Univ, France.
    Elhadi Adam, Rania Elhadi
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Optical and magneto-optical properties of zinc-oxide nanostructures grown by the low-temperature chemical route2018In: OXIDE-BASED MATERIALS AND DEVICES IX, SPIE-INT SOC OPTICAL ENGINEERING , 2018, Vol. 10533, article id UNSP 105331DConference paper (Refereed)
    Abstract [en]

    We demonstrate that the low temperature synthesis chemical route can be utilized to control the functionality of zinc oxide (ZnO) nanoparticles (NPs) and nanorods (NRs) for optical and magneto-optical performance. Different structural, optical, electro-and magneto-optical results will be displayed and analyzed. In the first part, we show how high quality ZnO NPs can be efficient for photodegradation using ultra-violet radiation. In the second part we will present our recent results on the control of the core defects in cobalt doped ZnO NR. Here and by using electron paramagnetic resonance (EPR) measurements, the substitution of Co2+ ions in the ZnO NRs crystal is shown. The relation between the incorporation and core defects concentration will be discussed. The findings give access to the magnetic anisotropy of ZnO NRs grown by the low temperature chemical route and can lead to demonstrate room temperature ferromagnetism in nanostructures with potential for different device applications.

  • 230.
    Willander, Magnus
    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.
    Zaman, Siama
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zainelabdin, A.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bano, Nargis
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Al-Hilli, Safaa
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Different interfaces to crystalline ZnO nanorods and their applications2009In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 6, no 12, p. 2683-2694Article in journal (Refereed)
    Abstract [en]

    In this paper we will demonstrate the growth of crystalline ZnO nanorods on different substrates including some of crystalline as well as amorphous nature. The application of these ZnO nanorods to optoelectronics and to bioelectronics will be highlighted. We demonstrate the fabrication of n-ZnO nano-rods/p-type substrates and fabricated light emitting diodes (LEDs) based on these structures. Among the presented LEDs, a hybrid configuration based on the integration of p-type polymers on flexible plastic provides a potential for developing large area white LEDs. Moreover, ZnO nanorods based intracellular measurements using bare and functionalized ZnO surfaces were demonstrated to be a valuable non-destructive tool for obtaining intracellular measurements paving the way for a wealth of intracellular information.

  • 231.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bano, Nargis
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Inorganic-organic ZnO Based Heterostructures for Lighting2009In: ECS transactionsArticle in journal (Refereed)
    Abstract [en]

    Here we present results on different organic and inorganic light emitting diodes (LED). The use of n-ZnO nanorods grown on different substrates forms the base of this new technology. p-type semiconducting as well as polymeric based substrates were used. The combination of n-ZnO nanorods and light emitting polymer(s) will lead to a LED with a broad emission spectrum and hence the possibility of producing white LEDs. Different issues regarding this hybrid new technology for lighting are to be discussed. Among them, we will present electrical, optical and electro-optical characteristics of different configurations of this hybrid technology regarding the polymer layer(s) choice. The light quality of the fabricated n-ZnO nanorods/p-type substrates LEDs will be shown and analyzed. Finally a comparison between this hybrid technology and other LEDs based on ZnO nanorods in combination with other inorganic p-type semiconductor is to be discussed.

  • 232.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Chirgwandi, Zakaria
    Gothenburg University, Sweden.
    Nour, Omer
    Gothenburg University, Sweden.
    A chip that creates micro-scale vortices in water and mimics biochemistry2006Other (Other (popular science, discussion, etc.))
  • 233.
    Willander, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Klason, P.
    Yang, L.L.
    Al Hilli, Safaa
    Zhao, Qingxiang
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Nour, Omer
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    ZnO nanowires: chemical growth, electro-deposition and application to intracellular nano-sensors2008In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 5, no 9, p. 3076-3083Article in journal (Refereed)
    Abstract [en]

    In this paper we present our results on growth, characterization, and nano-devices based on ZnO nano-structures. The ZnO nano-structures were grown by mainly two methods, the catalytic Vapor Liquid Solid (VLS) and the low temperature chemical growth. We show that by multiple coating combined with low temperature chemical growth, well aligned with size controlled ZnO nanowires on silicon substrates can be achieved. The dissolution, due to its important on the stability of ZnO nano-structures in aqueous medium, is then discussed and some preliminary experimental results are shown. Basic Optical characteristics of ZnO nano-rods are briefly discussed. Finally, electrochemical intracellular nano-sensors based on ZnO nano-wires are demonstrated as efficient nano-sensors for monitoring the human cell activity with minute pH changes. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • 234.
    Willander, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lozovik, Y. E.
    Russian Academy of Sciences .
    Zhao, Q.X.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Science and Technology.
    Hu, Q.-H.
    Gothenburg University.
    Klason, P.
    Gothenburg University.
    Excitonic effects in ZnO nanowires and hollow nanotubes2007In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6486, no 648614Article in journal (Refereed)
    Abstract [en]

    Energy levels and wave functions of ground and excited states of an exciton are calculated by the method of imaginary time. Energy levels as functions of radius of single and double wall nanotube are studied. Asymptotic behavior of energy levels at large and small values of the radius using perturbation theory and adiabatic approximation is considered. Spatially indirect exciton in semiconductor nanowire is also investigated. Experimental result from high quality reproducible ZnO nanowires grown by low temperature chemical engineering is presented. State of the art high brightness white light emitting diodes (HB-LEDs) are demonstrated from the grown ZnO nano-wires. The color temperature and color rendering index (CRI) of the HB-LEDs values was found to be (3250 K, 82), and (14000 K, 93), for the best LEDs, which means that the quality of light is superior to one obtained from GaN LEDs available on the market today. The role of VZn and Vo on the emission responsible for the white light band as well as the peak position of this important wide band is thoroughly investigated in a systematic way.

  • 235.
    Willander, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lozovik, Y.E.
    Merkulova, S.P.
    Nour, Omer
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Wadeasa, A.
    Klason, P.
    Nargis, B.
    Alvi, N.H.
    Kishwar, S.
    Photonic nano-devices and coherent phenomena in some low dimensional systems2008In: Invited: 214th Electrochemcial Society Meeting,2008, 2008Conference paper (Other academic)
  • 236.
    Willander, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lozovik, Y.E.
    Wadeasa, A.
    Nour, Omer
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Semenov, A.G.
    Vornrova, N.S.
    Light emission from different zinc oxide junctions and nanostructures2009In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Physica Status Solidi A, Vol. 206, no 5, p. 853-859Article in journal (Refereed)
    Abstract [en]

    We will discuss our experimental results for optical spectra produced by hole-injection from different p-type organic and inorganic materials into n-type ZnO nanowires. The influence of different growth techniques and conditions on the nanowires and their emission spectral characteristics will then be analyzed and discussed. The latest findings on the mixture of the green emission band responsible for visible light emission from ZnO and the blue light emission from the organic polymer will be presented. Different high brightness light emitting diodes (HB-LEDs) from our grown ZnO nanowires are demonstrated. The p-type multi layer organic structures contain PEDOT:PSS as hole injectors combined with a hole transporting layer, and in some structures, a final top electron blocking/hole barrier stepping layer is placed. The purpose of this layer is to adjust the hole and electron emission from the corresponding junction side to optimize the LED performance. Structural scanning electron microscopy (SEM), electrical (IV characteristics), photoluminescence (PL) and electroluminescence (EL) characteristics of these devices are displayed. Theoretically, we study the superfluidity of a two-dimensional system of excitonic polaritons in an optical microcavity with an embedded quantum well. Using the effective low-energy action for thermodynamic phase fluctuations, we obtain an expression for the analogue of the superfluid density in the system in terms of the “current–current” correlation function. The Kosterlits–Thouless transition temperature to the superfluid state as a function of the controlling parameters is calculated. Two methods are considered for producing traps for a polariton system in an optical microcavity. The behaviour of a two-component Bose condensate of photons and excitons is analyzed theoretically for both types of the trap. The Bose condensate is described by the coupled system of equations of the Gross–Pitaevskii type. The approximate wave functions and the spatial profiles of coupled photon and exciton condensates are obtained.

  • 237.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lozovik, Yu E
    Institute Spect, Moscow Region Russia .
    Wadeasa, Amal
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Semenov, A G
    Institute Spect, Moscow Region Russia .
    Voronova, N S
    Institute Spect, Moscow Region Russia .
    Erratum: Light emission from different ZnO junctions and nanostructures (vol 206, pg 853, 2009)2011In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 208, no 5, p. 1207-1207Article in journal (Refereed)
    Abstract [en]

    n/a

  • 238.
    Willander, Magnus
    et al.
    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.
    Applications of zinc oxide nanowires for biophotonics and bio-electronics2011Other (Other (popular science, discussion, etc.))
  • 239.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc Oxide Nanorods for White Light Emitting Diodes2009In: Journal of Jilin Normal University (Natural science edition), ISSN 1000-5277, Vol. 30, no 3, p. 1-10Article in journal (Refereed)
  • 240.
    Willander, Magnus
    et al.
    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.
    Zinc oxide nanowires for biomedical sensing and analysis2012In: Nanomedicine: Technologies and Applications / [ed] Thomas Webster, Philadelphia, U.S.A.: Woodhead Publishing Limited, 2012, p. 377-397Chapter in book (Other academic)
  • 241.
    Willander, Magnus
    et al.
    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.
    Ali, Sayed Usman
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc oxide nanostrucutres based bio and chemical extra- and intracellular sensors2011In: Portable chemical sensors: weapons against terrorism / [ed] D. P. Nikolelis, Springer, 2011, p. 305-322Chapter in book (Other academic)
    Abstract [en]

    In this chapter we present sensors based on ZnO nanostructures suitable for sensing in small volumes and can be used for intracellular as well as extracellular environments. The principle of the measurement is based on the potentiometric effect. The measurement electrodes were constructed by growing ZnO nanostructures on the tip of sub-micrometer glass pipettes and were used versus Ag/AgCl reference electrodes. By functionalizing the ZnO nanostructures based electrodes, the selectivity of the sensors can be tuned to detect the ion or the analyte in question. The developed sensors were used to measure the concentration of most of the common ions like calcium, potassium, sodium and magnesium. In addition different biological analytes were also measured. These include glucose, urine, uric acid and cholesterol. The developed sensors showed good sensitivity and a wide dynamic range and represent a step towards developing efficient sensor of interest for human health diagnostic.

  • 242.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bano, N.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sultana, K.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc oxide nanorod-based heterostructures on solid and soft substrates for white-light-emitting diode applications2009In: New Journal of Physics, E-ISSN 1367-2630, Vol. 11, no 125020Article in journal (Refereed)
    Abstract [en]

    ZnO nanorods with excellent optical and electro-optical emission characteristics were grown using high-and low-temperature techniques on solid and soft substrate materials. The solid crystalline substrates included p-4H-SiC and p-GaN, while the soft amorphous substrates included p-type polymers deposited on glass and flexible plastic. Two different growth approaches were used to produce these samples. We used the vapor-liquid-solid (VLS) technique (high temperature) and aqueous chemical growth (ACG), which is a low-temperature technique. These ZnO nanorod samples were characterized by room temperature photoluminescence (PL) and processed to fabricate light-emitting diodes (LEDs). The LED characteristics were further investigated by I-V and electroluminescence (EL). As observed by PL measurements, all samples revealed a sharp narrow ultraviolet (UV) peak due to band-edge emission, indicating the good crystalline quality of the grown ZnO nanorods. The origin of the different peaks within the visible region was correlated to different deep level defects reported earlier for ZnO. All fabricated LEDs showed EL providing a wide band extended through the whole visible spectrum and hence produced clear white light observable to the naked eye. The emitted color quality investigation showed that superior color quality was manifested in a high color rendering index and stable color under current variation, indicating that these heterojunction and hybrid LEDs have potential for the development of future light sources. The ZnO nanorod-based LEDs grown by low-temperature ACG on glass and flexible plastic can, after further development, be candidates for future large-area white-light sources.

  • 243.
    Willander, Magnus
    et al.
    Chalmers.
    Nour, Omer
    Chalmers.
    Jain, S.C.
    IMEC, Leuven, Belgium.
    Silicon germanium strained layers and heterostructures2004In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T114, p. 22-30Article in journal (Refereed)
    Abstract [en]

    The integration of strained-Si1-xGex into Si technology has enhanced the performance and extended the functionality of Si based circuits. The improvement of device performance is observed in both AC as well as DC characteristics of these devices. The category of such devices includes field effect as well as bipolar families. Speed performance in some based circuits has reached limits previously dominated by III-V heterostructures based devices. In addition, for some optoelectronics applications including photodetectors it is now possible to easily integrate strained-Si1-xGex based optical devices into standard Silicon technology. The impact of integrating strained and relaxed Si1-xGex alloys into Si technology is important. It has lead to stimulate Si research as well as offers easy options for performances that requires very complicated and costly process if pure Si has to be used. In this paper we start by discussing the strain and stability of Si1-xGex alloys. The origin and the process responsible for transient enhanced diffusion (TED) in highly doped Si containing layers will be mentioned. Due to the importance of TED for thin highly doped Boron strained-Si1-xGex layers and its degrading consequences, possible suppression design methods will be presented. Quantum well p-channel MOSFETs (QW-PMOSFETs) based on thin buried QW are solution to the low speed and weak current derivability. Different aspects of designing these devices for a better performance are briefly reviewed. Other FETs based on tensile strained Si on relaxed Si1-xGex for n-channel and modulation doped field effect transistors (MODFETs) showed excellent performance. Record AC performance well above 200GHz for f(max) is already observed and this record is expected to increase in the coming years. Heterojunction bipolar transistors (HPTs) with thin strained-Si1-xGex highly doped base have lead to optimize the performance of the bipolar technology for many applications easily. The strategies of design and the most important designs of HBTs for optimum AC as well as DC are discussed in details. This technology is now mature enough and that is manifested in the appearance in the market nowadays. Si1-xGex based FETs circuits compatible with standard Si CMOS processes are soon expected to appear in the market. Finally, we briefly discuss the recent advances in Si1-xGex based infrared photodetectors.

  • 244.
    Willander, Magnus
    et al.
    Göteborg University.
    Nour, Omer
    Göteborg University.
    Lozovik, YE
    Russian Academy of Sciences.
    Al-Hilli, SM
    Göteborg University.
    Chiragwandi, Z
    Göteborg University.
    Hu, QH
    Göteborg University.
    Zhao, QX
    Göteborg University.
    Klason, P
    Göteborg University.
    Solid and soft nanostructured materials: Fundamentals and applications2005In: MICROELECTRONICS JOURNAL, ISSN 0026-2692, Vol. 36, no 11, p. 940-949Article in journal (Refereed)
    Abstract [en]

    The scientific work worldwide on nanostructured materials is extensive as well as the work on the applications of nanostructured materials. We will review quasi two-, one- and zero-dimensional solid and soft materials and their applications. We will restrict ourselves to a few examples from partly fundamental aspects and partly from application aspects. We will start with trapping of excitons in semiconductor nanostructures. The subjects are: physical realizations, phase diagrams, traps, local density approximations, and mesoscopic condensates. From these fundamental questions in solid nanomaterials we will move to trapping of molecules in water using nanostructured electrodes. We will also discuss how to manipulate water (create vortices) by nanostructure materials. The second part deals with nanorods (nano-wires). Particularly we will exemplify with ZnO nanorods. The reason for this is that ZnO has: a very strong excitons binding energy (60 meV) and strong photon-excitons coupling energy, a strong tendency to create nanostructures, and properties which make the material of interest for both optoelectronics and for medical applications. We start with the growth of crystalline ZnO nanorods on different substrates, both crystalline (silicon, silicon carbide, sapphire, etc) and amorphous substrates (silicon dioxide, plastic materials, etc) for temperatures from 50 degrees C up to 900 degrees C. The optical properties and crystalline properties of the nanorods will be analyzed. Applications from optoelectronics (lasers, LEDs, lamps, and detectors) are analyzed and also medical applications like photodynarnic cancer therapy are taken up. The third part deals with nano-particles in ZnO for sun screening. Skin cancer due to the exposure from the sun can be prevented by ZnO particles in a paste put on the exposed skin.

  • 245.
    Willander, Magnus
    et al.
    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.
    Qadir, Muhammad Israr
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    One- and two-dimensional nanostructures for chemical- and biosensing2011In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 25, p. 745-748Article in journal (Refereed)
    Abstract [en]

    Nanostructures have been very popular for several years to do research on sensing. In this paper we will demonstrate the advantage of using nanowires of zinc oxide (ZnO) as one dimensional structure for potentiometric measurements in biological environments. The developed procedures show suitability for the accurate determination of most of the important metal ions and to characterize cells and thin bio-layers. We will also show how to use these structures for biosensing of glucose, cholesterol, and the application of extended gate metal oxide semiconductor field effect transistors as the signal transducer. In the second part, we will show how to use a two-dimensional nanostructure, specifically graphene, for cholesterol and glucose biosensing.

    Download full text (pdf)
    fulltext
  • 246.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zhao, Qingxiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Yang, Lili
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lorenz, M
    University of Leipzig.
    Cao, B Q
    University of Leipzig.
    Zuniga Perez, J
    University of Leipzig.
    Czekalla, C
    University of Leipzig.
    Zimmermann, G
    University of Leipzig.
    Grundmann, M
    University of Leipzig.
    Bakin, A
    Tech University Carolo Wilhelmina Braunschweig.
    Behrends, A
    Tech University Carolo Wilhelmina Braunschweig.
    Al-Suleiman, M
    Tech University Carolo Wilhelmina Braunschweig.
    El-Shaer, A
    Tech University Carolo Wilhelmina Braunschweig.
    Che Mofor, A
    Tech University Carolo Wilhelmina Braunschweig.
    Postels, B
    Tech University Carolo Wilhelmina Braunschweig.
    Waag, A
    Tech University Carolo Wilhelmina Braunschweig.
    Boukos, N
    Natl Centre Science Research Demokritos.
    Travlos, A
    Natl Centre Science Research Demokritos.
    Kwack, H S
    CNRS.
    Guinard, J
    CNRS.
    Le Si Dang, D
    CNRS.
    Zinc oxide nanorod based photonic devices: recent progress in growth, light emitting diodes and lasers2009In: NANOTECHNOLOGY, ISSN 0957-4484, Vol. 20, no 33, p. 332001-Article, review/survey (Refereed)
    Abstract [en]

    Zinc oxide (ZnO), with its excellent luminescent properties and the ease of growth of its nanostructures, holds promise for the development of photonic devices. The recent advances in growth of ZnO nanorods are discussed. Results from both low temperature and high temperature growth approaches are presented. The techniques which are presented include metal-organic chemical vapour deposition (MOCVD), vapour phase epitaxy (VPE), pulse laser deposition (PLD), vapour-liquid-solid (VLS), aqueous chemical growth (ACG) and finally the electrodeposition technique as an example of a selective growth approach. Results from structural as well as optical properties of a variety of ZnO nanorods are shown and analysed using different techniques, including high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), photoluminescence (PL) and cathodoluminescence (CL), for both room temperature and for low temperature performance. These results indicate that the grown ZnO nanorods possess reproducible and interesting optical properties. Results on obtaining p-type doping in ZnO micro- and nanorods are also demonstrated using PLD. Three independent indications were found for p-type conducting, phosphorus-doped ZnO nanorods: first, acceptor-related CL peaks, second, opposite transfer characteristics of back-gate field effect transistors using undoped and phosphorus doped wire channels, and finally, rectifying I-V characteristics of ZnO: P nanowire/ZnO:Ga p-n junctions. Then light emitting diodes (LEDs) based on n-ZnO nanorods combined with different technologies (hybrid technologies) are suggested and the recent electrical, as well as electro-optical, characteristics of these LEDs are shown and discussed. The hybrid LEDs reviewed and discussed here are mainly presented for two groups: those based on n-ZnO nanorods and p-type crystalline substrates, and those based on n-ZnO nanorods and p-type amorphous substrates. Promising electroluminescence characteristics aimed at the development of white LEDs are demonstrated. Although some of the presented LEDs show visible emission for applied biases in excess of 10 V, optimized structures are expected to provide the same emission at much lower voltage. Finally, lasing from ZnO nanorods is briefly reviewed. An example of a recent whispering gallery mode (WGM) lasing from ZnO is demonstrated as a way to enhance the stimulated emission from small size structures.

  • 247.
    Willander, Magnus
    et al.
    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.
    Amin, Gul
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zainelabdin, A.
    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.
    Zinc oxide and copper oxide nanostructures: Fundamentals and applications2012In: Materials Research Society Symposium Proceedings: vol 1406, Warrendale, Pa.; Materials Research Society; 1999 , 2012, Vol. 1406, p. 3-10Conference paper (Refereed)
    Abstract [en]

    Copper oxide (CuO) and zinc oxide (ZnO) nanostructures complement each other since CuO is unintentional p-type and ZnO unintentional n-type. Using the low temperature chemical growth approach, the effect on morphology of varying the pH of the grown ZnO nanostructures and CuO micro structures is monitored. For both materials the variation of the pH was found to lead to a large variation on the morphology achieved. The grown ZnO NRs and CuO micro flowers material were used to fabricate devices. We demonstrate results from ZnO nanorods (NRs)/polymer p-n hybrid heterojunctions chemically grown on paper and using a process on paper for light emitting diodes (LEDs) applications as well as some large area light emitting diodes LEDs. The growth of CuO micro flowers indicated good quality material for sensing applications. The grown CuO micro flowers were employed as pH sensors. The results indicated a superior performance as expect due to the catalytic properties of this material. © 2012 Materials Research Society.

  • 248.
    Willander, Magnus
    et al.
    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.
    Fakhar-e-Alam, M.
    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, Physics and Electronics. Linköping University, The Institute of Technology.
    Israr Qadir, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Sultana, Kishwar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ali, Syed M. Usman
    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.
    Applications of Zinc Oxide Nanowires for Bio-photonics and Bio-electronics2011In: Proceedings of SPIE Volume 7940 / [ed] Ferechteh Hosseini Teherani, David C. Look, David J. Rogers, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011Conference paper (Other academic)
    Abstract [en]

    Using zinc oxide (ZnO) nanostructures, nanorods (NRs) and nanoparticles (NPs) grown on different substrates (sub-micrometer glass pipettes, thin silver wire and on plastic substrate) different bio-sensors were demonstrated. The demonstrated sensors are based on potentiometric approach and are sensitive to the ionic metals and biological analyte in question. For each case a selective membrane or enzyme was used. The measurements were performed for intracellular environment as well as in some cases (cholesterol and uric acid). The selectivity in each case is tuned according to the element to be sensed. Moreover we also developed photodynamic therapy approach based on the use of ZnO NRs and NPs. Necrosis/apoptosis was possible to achieve for different types of cancerous cell. The results indicate that the ZnO with its UV and white band emissions is beneficial to photodynamic therapy technology.

  • 249.
    Willander, Magnus
    et al.
    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.
    Sadaf, Jamil Rana
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Qadir, Muhammad Israr
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Zaman, Saima
    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.
    Bano, Nargis
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain, Ijaz
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Luminescence from Zinc Oxide Nanostructures and Polymers and their Hybrid Devices2010In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 3, no 4, p. 2643-2667Article, review/survey (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) is a strong luminescent material, as are several polymers. These two materials have distinct drawbacks and advantages, and they can be combined to form nanostructures with many important applications, e. g., large-area white lighting. This paper discusses the origin of visible emission centers in ZnO nanorods grown with different approaches. White light emitting diodes (LEDs) were fabricated by combining n-ZnO nanorods and hollow nanotubes with different p-type materials to form heterojunctions. The p-type component of the hybrids includes p-SiC, p-GaN, and polymers. We conclude by analyzing the electroluminescence of the different light emitting diodes we fabricated. The observed optical, electrical, and electro-optical characteristics of these LEDs are discussed with an emphasis on the deep level centers that cause the emission.

    Download full text (pdf)
    fulltext
  • 250.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    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.
    Zainelabdin, A
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bano, Nargis
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, I
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes2011In: JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN 0022-3727, Vol. 44, no 22, p. 224017-Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods (NRs) grown on flexible plastic as substrate using a low temperature approach (down to 50 degrees C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO NRs on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT : PSS) for hole injection with an ionization potential of 5.1 eV and poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO NRs are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red-emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope, x-ray diffraction (XRD), current-voltage (I-V) characteristics, room temperature photoluminescence (PL) and EL. The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.

    Download full text (pdf)
    fulltext
23456 201 - 250 of 276
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf