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  • 1.
    Abrikossova, Natalia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Skoglund, Caroline
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska högskolan.
    Ahrén, Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Bengtsson, Torbjorn
    University of Örebro, Sweden .
    Uvdal, Kajsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Effects of gadolinium oxide nanoparticles on the oxidative burst from human neutrophil granulocytes2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 27, s. 275101-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

  • 2.
    Berggren, Karl-Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sadreev, A.F.
    Kirensky Institute of Physics, 660036, Krasnoyarsk, Russian Federation.
    Starikov, Anton
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Quantum chaos among nodal points and streamlines at ballistic electron transport through open quantum dots2001Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 12, nr 4, s. 562-565Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We trace signatures of quantum chaos in the distribution of nodal points and streamlines for coherent electron transport through different types of quantum dots (chaotic and regular). We have calculated normalized distribution functions for the nearest distances between nodal points and found that this distribution may be used as a signature of quantum chaos for electron transport in open systems. Different chaotic billiards show the same characteristic distribution function for nodal points. This signature of quantum chaos is well reproduced using well known approaches for chaotic wavefunctions. We have also investigated the quantum flows which display some remarkable features.

  • 3.
    Berggren, Karl-Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Yakimenko, I.I.
    Bychkov, A.M.
    Centre for Quantum Computation, Clarendon Laboratory, Oxford OX1 3PU, United Kingdom, Moscow State Engineering Physics Institute, Technical University, 115409 Moscow, Russian Federation.
    On the role of electron exchange and correlation in semiconductor quantum dots2001Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 12, nr 4, s. 529-532Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Spontaneous magnetization of single and coupled quantum dots formed by lateral confinement of a high-mobility two-dimensional electron gas is studied for a realistic GaAs/AlGaAs heterostructure. The modelling of the device takes into account contributions from a patterned gate, doping, surface states, and mirror charges. To explore the magnetic properties we use the Kohn-Sham local spin-density formalism including the contributions from electron correlation and exchange. We show by explicit calculations that the exchange is the dominant mechanism driving a spontaneous magnetization of a dot. The correlation potential reduces the amount of level splitting and usually affects the electron content in the dot at a given gate voltage. These effects are, however, small and may be neglected under present circumstances. Single dots with up to 50 electrons have been studied.

  • 4.
    Beyer, Jan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Buyanova, Irina A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Suraprapapich, Suwaree
    UC San Diego, USA.
    Tu, Charles
    UC San Diego, USA.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Spin injection in lateral InAs quantum dot structures by optical orientation spectroscopy2009Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, nr 37, s. 375401-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optical spin injection is studied in novel laterally-arranged self-assembled InAs/GaAs quantum dot structures, by using optical orientation measurements in combination with tunable laser spectroscopy. It is shown that spins of uncorrelated free carriers are better conserved during the spin injection than the spins of correlated electrons and holes in an exciton. This is attributed to efficient spin relaxation promoted by the electron–hole exchange interaction of the excitons. Our finding suggests that separate carrier injection, such as that employed in electrical spin injection devices, can be advantageous for spin conserving injection. It is also found that the spin injection efficiency decreases for free carriers with high momentum, due to the acceleration of spin relaxation processes.

  • 5.
    Beyer, Jan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Suraprapapich, S
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 13, s. 135705-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hanle effect in InAs/GaAs quantum dots (QDs) is studied under optical orientation as a function of temperature over the range of 150-300 K, with the aim to understand the physical mechanism responsible for the observed sharp increase of electron spin polarization with increasing temperature. The deduced spin lifetime Ts of positive trions in the QDs is found to be independent of temperature, and is also insensitive to excitation energy and density. It is argued that the measured Ts is mainly determined by the longitudinal spin flip time (T1) and the spin dephasing time (T2 *) of the studied QD ensemble, of which both are temperatureindependent over the studied temperature range and the latter makes a larger contribution. The observed sharply rising of the QD spin polarization degree with increasing temperature, on the other hand, is shown to be induced by an increase in spin injection efficiency from the barrier/wetting layer and also by a moderate increase in spin detection efficiency of the QD.

  • 6.
    Beyer, Jan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Suraprapapich, S
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Hanle effect in InAs/GaAs quantum dots up to room temperatures2011Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528Artikkel i tidsskrift (Fagfellevurdert)
  • 7.
    Burns, Joshua M
    et al.
    Department of Bioengineering, University of California, Riverside, CA 92521, USA.
    Saager, Rolf B.
    Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA 92612, USA.
    Majaron, Boris
    Department of Complex Matter, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
    Jia, Wangcun
    Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA 92612, USA.
    Anvari, Bahman
    Department of Bioengineering, University of California, Riverside, CA 92521, USA.
    Optical properties of biomimetic probes engineered from erythrocytes2016Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, nr 3, artikkel-id 035101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Light-activated theranostic materials offer a potential platform for optical imaging and phototherapeutic applications. We have engineered constructs derived from erythrocytes, which can be doped with the FDA-approved near infrared (NIR) chromophore, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-mimicking transducers (NETs). Herein, we investigated the effects of changing the NETs mean diameter from micron- (≈4 μm) to nano- (≈90 nm) scale, and the ICG concentration utilized in the fabrication of NETs from 5 to 20 μM on the resulting absorption and scattering characteristics of the NETs. Our approach consisted of integrating sphere-based measurements of light transmittance and reflectance, and subsequent utilization of these measurements in an inverse adding-doubling algorithm to estimate the absorption (μ a) and reduced scattering (μ s') coefficients of these NETs. For a given NETs diameter, values of μ a increased over the approximate spectral band of 630–860 nm with increasing ICG concentration. Micron-sized NETs produced the highest peak value of μ a when using ICG concentrations of 10 and 20 μM, and showed increased values of μ s' as compared to nano-sized NETs. Spectral profiles of μ s' for these NETs showed a trend consistent with Mie scattering behavior for spherical objects. For all NETs investigated, changing the ICG concentration minimally affected the scattering characteristics. A Monte Carlo-based model of light distribution showed that the presence of these NETs enhanced the fluence levels within simulated blood vessels. These results provide important data towards determining the appropriate light dosimetry parameters for an intended light-based biomedical application of NETs.

  • 8.
    Buyanova, Irina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Dilute nitrides-based nanowires-a promising platform for nanoscale photonics and energy technology2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 29, artikkel-id 292002Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Dilute nitrides are novel III-V-N semiconductor alloys promising for a great variety of applications ranging from nanoscale light emitters and solar cells to energy production via photoelectrochemical reactions and to nano-spintronics. These alloys have become available in the one-dimensional geometry only most recently, thanks to the advances in the nanowire (NW) growth utilizing molecular beam epitaxy. In this review we will summarize growth approaches currently utilized for the fabrication of such novel dilute nitride-based NWs, discuss their structural, defect-related and optical properties, as well as provide several examples of their potential applications.

  • 9. Bychkov, A.M.
    et al.
    Yakimenko, I.I.
    Berggren, Karl-Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Spin-dependent electron behaviour in quantum point contacts2000Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 11, nr 4, s. 318-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of spontaneous spin polarization in quantum point contacts (QPCs) is investigated by self-consistent modelling within the Kohn-Sham local spin-density formalism. The existence of the spin-polarized state of the QPC channel in the low-density regime is shown to change the value and the shape of the effective potential barrier for up- and down-spin electrons. We suggest that this effect can be relevant to the explanation of the anomalous 0.7-structure in the QPC conductance and may assist spin injection in potential spintronic devices.

  • 10.
    Cattelan, Mattia
    et al.
    School of Chemistry, University of Bristol, Cantocks Close, Bristol, United Kingdom.
    Vagin, Mikhail
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Fox, Neil A.
    School of Chemistry, University of Bristol, Cantocks Close, Bristol, United Kingdom.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Shtepliuk, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Anodization study of epitaxial graphene: insights on the oxygen evolution reaction of graphitic materials2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 28, artikkel-id 285701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The photoemission electron microscopy and x-ray photoemission spectroscopy were utilized for the study of anodized epitaxial graphene (EG) on silicon carbide as a fundamental aspect of the oxygen evolution reaction on graphitic materials. The high-resolution analysis of surface morphology and composition quantified the material transformation during the anodization. We investigated the surface with lateral resolution amp;lt;150 nm, revealing significant transformations on the EG and the role of multilayer edges in increasing the film capacitance.

  • 11.
    Chalangar, Ebrahim
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Halmstad Univ, Sweden.
    Machhadani, Houssaine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Lim, Seung-Hyuk
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Halmstad Univ, Sweden; Lund Univ, Sweden; Lund Univ, Sweden.
    Influence of morphology on electrical and optical properties of graphene/Al-doped ZnO-nanorod composites2018Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 29, nr 41, artikkel-id 415201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of future 3D-printed electronics relies on the access to highly conductive inexpensive materials that are printable at low temperatures (amp;lt;100 degrees C). The implementation of available materials for these applications are, however, still limited by issues related to cost and printing quality. Here, we report on the simple hydrothermal growth of novel nanocomposites that are well suited for conductive printing applications. The nanocomposites comprise highly Al-doped ZnO nanorods grown on graphene nanoplatelets (GNPs). The ZnO nanorods play the two major roles of (i) preventing GNPs from agglomerating and (ii) promoting electrical conduction paths between the graphene platelets. The effect of two different ZnO-nanorod morphologies with varying Al-doping concentration on the nanocomposite conductivity and the graphene dispersity are investigated. Time-dependent absorption, photoluminescence and photoconductivity measurements show that growth in high pH solutions promotes a better graphene dispersity, higher doping levels and enhanced bonding between the graphene and the ZnO nanorods. Growth in low pH solutions yields samples characterized by a higher conductivity and a reduced number of surface defects. These samples also exhibit a large persistent photoconductivity attributed to an effective charge separation and transfer from the nanorods to the graphene platelets. Our findings can be used to tailor the conductivity of novel printable composites, or for fabrication of large volumes of inexpensive porous conjugated graphene-semiconductor composites.

  • 12.
    Dong, Suzi
    et al.
    Department of Chemistry, National University of Singapore.
    Fan, HM
    Department of Physics, National University of Singapore.
    Zhang, Xuanjun
    Department of Chemistry, National University of Singapore.
    Loh, Kian Ping
    Department of Chemistry, National University of Singapore.
    Cheng, C-L
    Department of Physics, National Dong Hwa University.
    SOW, CH
    Department of Physics, National University of Singapore.
    Foo, YL
    Institute of Materials Research and Engineering, Singapore.
    An effective surface-enhanced Raman scattering template based on a Ag nanocluster–ZnO nanowire array2009Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, nr 17, s. 175705-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An effective surface-enhanced Raman scattering (SERS) template based on a 3D hybrid Ag nanocluster (NC)-decorated ZnO nanowire array was fabricated through a simple process of depositing Ag NCs on ZnO nanowire arrays. The effects of particle size and excitation energy on the Raman scattering in these hybrid systems have been investigated using rhodamine 6G as a standard analyte. The results indicate that the hybrid nanosystem with 150 nm Ag NCs produces a larger SERS enhancement factor of 3.2 × 108, which is much higher than that of 10 nm Ag NCs (6.0 × 106) under 532 nm excitation energy. The hybrid nanowire arrays were further applied to obtain SERS spectra of the two-photon absorption (TPA) chromophore T7. Finite-difference time-domain simulations reveal the presence of an enhanced field associated with inter-wire plasmon coupling of the 150 nm Ag NCs on adjacent ZnO nanowires; such a field was absent in the case of the 10 nm Ag NC-coated ZnO nanowire. Such hybrid nanosystems could be used as SERS substrates more effectively than assembled Ag NC film due to the enhanced light-scattering local field and the inter-wire plasmon-enhanced electromagnetic field.

  • 13.
    dos Santos, Renato B.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. University of Federal Bahia, Brazil.
    de Brito Mota, F.
    University of Federal Bahia, Brazil.
    Rivelino, R.
    University of Federal Bahia, Brazil.
    Kakanakova-Gueorguie, Anelia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Gueorguiev, Gueorgui Kustov
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Van der Waals stacks of few-layer h-AlN with graphene: an ab initio study of structural, interaction and electronic properties2016Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 27, nr 14, s. 145601-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Graphite-like hexagonal AlN (h-AlN) multilayers have been experimentally manifested and theoretically modeled. The development of any functional electronics applications of h-AlN would most certainly require its integration with other layered materials, particularly graphene. Here, by employing vdW-corrected density functional theory calculations, we investigate structure, interaction energy, and electronic properties of van der Waals stacking sequences of few-layer h-AlN with graphene. We find that the presence of a template such as graphene induces enough interlayer charge separation in h-AlN, favoring a graphite-like stacking formation. We also find that the interface dipole, calculated per unit cell of the stacks, tends to increase with the number of stacked layers of h-AlN and graphene.

  • 14. Esmaeili, M.
    et al.
    Harati Zadeh, Hamid
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Paskov, Plamen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Iwaya, M.
    Kamiyama, S.
    Amano, H.
    Akasaki, I
    Photoluminescence study of MOCVD-grown GaN/AlGaN MQW nanostructures: Influence of Al composition and Si doping2007Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 18, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed study of low-temperature photoluminescence (PL) in GaN/AlGaN multiple quantum well (MQW) nanostructures has been reported. We have investigated the effect of Si doping and Al content on PL spectra and PL decay time of these structures. The temperature dependence of radiative as well as non-radiative lifetimes have been evaluated between 2K and room temperature for different Si doping. We found that radiative recombination at higher temperatures even up to RT is stronger in the doped sample, compared to the undoped one. Hole localization in GaN/AlGaN MQWs with different compositions of Al is demonstrated via PL transient decay times and LO phonon coupling. It is found that there is an increasing of the decay time at the PL peak emission with increasing Al composition. For the undoped sample, a non-exponential PL decay behaviour at 2K is attributed to localized exciton recombination. A slight upshift in QWs PL peak with increasing Al composition is observed, which is counteracted by the expected rise of the internal QW electric field with increasing Al. The localization energies have been evaluated by studying the variation of the QW emission versus temperature and we found out that the localization energy increases with increasing Al composition. © IOP Publishing Ltd.

  • 15.
    Forsberg, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Serban, Alexandra
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Poenaru, Iuliana
    Fraunhofer ISC, Project Group Materials Recycling and Resource Strategy IWKS, Hanau, Germany.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Junaid, Mohammad
    RWTH Aachen University, Aachen, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Stacking fault related luminescence in GaN nanorods2015Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optical and structural properties are presented for GaN nanorods grown in the [0001]direction on Si(111) substrates by direct-current reactive magnetron sputter epitaxy.Transmission electron microscopy reveals clusters of dense stacking faults (SFs) regularlydistributed along the c-axis. A strong emission at ~3.42 eV associated with basal plane SFsdemonstrates thermal stability up to room temperatures together with a relatively shortrecombination time suggesting carrier localization in the system similar to multiple quantumwells.

  • 16.
    Freitas, Rafael RQ
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. University of Federal Bahia, Brazil.
    de Brito Mota, F.
    University of Federal Bahia, Brazil.
    Rivelino, R.
    University of Federal Bahia, Brazil.
    de Castilho, C. M. C.
    University of Federal Bahia, Brazil.
    Kakanakova-Gueorguie, Anelia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Gueorguiev, Gueorgui Kostov
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tuning band inversion symmetry of buckled III-Bi sheets by halogenation2016Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 27, nr 5, s. 1-11, artikkel-id 055704Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First-principles calculations are employed to investigate structural, electronic and topological insulating properties of XBi (X = B, Al, Ga, and In) monolayers upon halogenation. It is known that Y-XBi (X = Ga, In, Tl; Y = F, Cl, Br, I) can originate inversion-asymmetric topological insulators with large bulk band gaps. Our results suggest that Y-XBi (X = B, Al; Y = F, Cl, Br, I) may also result in nontrivial topological insulating phases. Despite the lower atomic number of B and Al, the spin-orbit coupling opens a band gap of about 400 meV in Y-XBi (X = B, Al), exhibiting an unusual electronic behavior for practical applications in spintronics. The nature of the bulk band gap and Dirac-cone edge states in their nanoribbons depends on the group-III elements and Y chemical species. They lead to a chemical tunability, giving rise to distinct band inversion symmetries and exhibiting Rashba-type spin splitting in the valence band of these systems. These findings indicate that a large family of Y-XBi sheets can exhibit nontrivial topological characteristics, by a proper tuning, and open a new possibility for viable applications at room temperature.

  • 17.
    Gholami, M.
    et al.
    Physics Department, Shahrood University of Technology, PO Box 316, 3619995161, Shahrood, Iran, Department of Science, Islamic Azad University, Damghan Branch, Damghan, Iran.
    Haratizadeh, H.
    Physics Department, Shahrood University of Technology, PO Box 316, 3619995161, Shahrood, Iran, Department of Physics, Chemistry and Biology, Linkoping University, SE-581 581 83 Linkoping, Sweden.
    Esmaeili, M.
    Physics Department, Shahrood University of Technology, PO Box 316, 3619995161, Shahrood, Iran, Department of Science, Islamic Azad University, Damghan Branch, Damghan, Iran.
    Amiri, R.
    Physics Department, Shahrood University of Technology, PO Box 316, 3619995161, Shahrood, Iran.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Hammar, M.
    Department of Microelectronics and Applied Physics, School of Information and Communication Technology, Royal Institute of Technology (KTH), 16440 Kista-Stocholm, Sweden.
    Alternation of band gap and localization of excitons in InGaNAs nanostructures with low nitrogen content2008Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 19, nr 31, s. 315705-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Continuous wave photoluminescence (cw PL) spectroscopy has been used to study the optical properties of a set of InGaNAs epilayers and single quantum wells with nitrogen concentration less than a few per cent at different temperatures and different excitation powers. We found that nitrogen has a critical role on the emission light of InGaNAs nanostructures and the recombination mechanism. The incorporation of a few per cent of nitrogen leads to shrinkage of the InGaNAs band gap. The physical origin of such band gap reduction has been investigated both experimentally and theoretically by using a band anticrossing model. We have found that localization of excitons that have been caused by incorporation of a few per cent of nitrogen in these structures is the main explanation of such anomalous behavior observed in the low-temperature photoluminescence spectra of these nanostructures. The localization energies of carriers have been evaluated by studying the variation of the quantum well (QW) emission versus temperature, and it was found that the localization energy increases with increasing nitrogen composition. Our data also show that, with increasing excitation intensity, the PL peak position moves to higher energies (blue shift) due to the filling of localized states and capture centers for excitons by photo-generated carriers. © IOP Publishing Ltd.

  • 18.
    Giannazzo, F.
    et al.
    CNR, Italy.
    Shtepliuk, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Iakimov, Tihomir
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Kakanakova-Gueorguieva, Anelia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Schiliro, E.
    CNR, Italy.
    Fiorenza, P.
    CNR, Italy.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Probing the uniformity of hydrogen intercalation in quasi-free-standing epitaxial graphene on SiC by micro-Raman mapping and conductive atomic force microscopy2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 28, artikkel-id 284003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, micro-Raman mapping and conductive atomic force microscopy (C-AFM) were jointly applied to investigate the structural and electrical homogeneity of quasi-free-standing monolayer graphene (QFMLG), obtained by high temperature decomposition of 4H-SiC(0001) followed by hydrogen intercalation at 900 degrees C. Strain and doping maps, obtained by Raman data, showed the presence of sub-micron patches with reduced hole density correlated to regions with higher compressive strain, probably associated with a locally reduced hydrogen intercalation. Nanoscale resolution electrical maps by C-AFM also revealed the presence of patches with enhanced current injection through the QFMLG/SiC interface, indicating a locally reduced Schottky barrier height (Phi(B)). The Phi(B) values evaluated from local I-V curves by the thermionic emission model were in good agreement with the values calculated for the QFMLG/SiC interface using the Schottky-Mott rule and the graphene holes density from Raman maps. The demonstrated approach revealed a useful and non-invasive method to probe the structural and electrical homogeneity of QFMLG for future nano-electronics applications.

  • 19. Heyman, A.
    et al.
    Yakimenko, I.I.
    Berggren, Karl-Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Band structure and spin polarization for a one-dimensional array of quantum point contacts2004Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 15, nr 1, s. 143-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have numerically studied the band structure and the spin polarization effect in a periodic one-dimensional array of quantum point contacts (QPCs) formed in a two-dimensional electron gas in a plane-layered semiconductor system. In this study we used a self-consistent model developed within the framework of the Kohn-Sham local spin-density formalism. We have found that the band structure contains a mixture of flat and dispersed bands, and the role of transverse modes in the formation of such a band structure has been clearly demonstrated. We have also shown that spin polarization occurs mainly in the regions occupied by the QPCs and that it is qualitatively similar to the spin polarization in a single QPC.

  • 20.
    Janssen, Xander J. A.
    et al.
    Delft University of Technology, Netherlands.
    Jonsson, Magnus P.
    Delft University of Technology, Netherlands.
    Plesa, Calin
    Delft University of Technology, Netherlands.
    Soni, Gautam V.
    Delft University of Technology, Netherlands.
    Dekker, Cees
    Delft University of Technology, Netherlands.
    Dekker, Nynke H.
    Delft University of Technology, Netherlands.
    Rapid manufacturing of low-noise membranes for nanopore sensors by trans-chip illumination lithography2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 47, artikkel-id 475302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, the concept of nanopore sensing has matured from a proof-of-principle method to a widespread, versatile technique for the study of biomolecular properties and interactions. While traditional nanopore devices based on a nanopore in a single layer membrane supported on a silicon chip can be rapidly fabricated using standard microfabrication methods, chips with additional insulating layers beyond the membrane region can provide significantly lower noise levels, but at the expense of requiring more costly and time-consuming fabrication steps. Here we present a novel fabrication protocol that overcomes this issue by enabling rapid and reproducible manufacturing of low-noise membranes for nanopore experiments. The fabrication protocol, termed trans-chip illumination lithography, is based on illuminating a membrane-containing wafer from its backside such that a photoresist (applied on the wafers top side) is exposed exclusively in the membrane regions. Trans-chip illumination lithography permits the local modification of membrane regions and hence the fabrication of nanopore chips containing locally patterned insulating layers. This is achieved while maintaining a well-defined area containing a single thin membrane for nanopore drilling. The trans-chip illumination lithography method achieves this without relying on separate masks, thereby eliminating time-consuming alignment steps as well as the need for a mask aligner. Using the presented approach, we demonstrate rapid and reproducible fabrication of nanopore chips that contain small (12 mu m x 12 mu m) free-standing silicon nitride membranes surrounded by insulating layers. The electrical noise characteristics of these nanopore chips are shown to be superior to those of simpler designs without insulating layers and comparable in quality to more complex designs that are more challenging to fabricate.

  • 21.
    Jansson, Mattias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Francaviglia, Luca
    Ecole Polytech Fed Lausanne, Switzerland.
    La, Rui
    Univ Calif San Diego, CA 92093 USA.
    Balagula, Roman
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Stehr, Jan Eric
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Tu, Charles W.
    Univ Calif San Diego, CA 92093 USA.
    Morral, Anna Fontcuberta I
    Ecole Polytech Fed Lausanne, Switzerland; Ecole Polytech Fed Lausanne, Switzerland.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Increasing N content in GaNAsP nanowires suppresses the impact of polytypism on luminescence2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 40, artikkel-id 405703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cathodoluminescence (CL) and micro-photoluminescence spectroscopies are employed to investigate effects of structural defects on carrier recombination in GaNAsP nanowires (NWs) grown by molecular beam epitaxy on Si substrates. In the NWs with a low N content of 0.08%, these defects are found to promote non-radiative (NR) recombination, which causes spatial variation of the CL peak position and its intensity. Unexpectedly, these detrimental effects can be suppressed even by a small increase in the nitrogen composition from 0.08% to 0.12%. This is attributed to more efficient trapping of excited carriers/excitons to the localized states promoted by N-induced localization and also the presence of other NR channels At room temperature, the structural defects no longer dominate in carrier recombination even in the NWs with the lower nitrogen content, likely due to increasing importance of other recombination channels. Our work underlines the need in eliminating important thermally activated NR defects, other than the structural defects, for future optoelectronic applications of these NWs.

  • 22.
    Jemsson, Tomas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Machhadani, Houssaine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik K
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid2015Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 6, s. 065702-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on excitonic single photon emission and biexcitonic photon bunching from an InGaN quantum dot formed on the apex of a hexagonal GaN micropyramid. An approach to suppress uncorrelated emission from the pyramid base is proposed, a metal lm is demonstrated to eectively screen background emission and thereby signicantly enhance the signal-to-background ratio of the quantum dot emission. As a result, the second order coherence function at zero time delay g(2)(0) is signicantly reduced (to g(2)(0) = 0.24, raw value) for the excitonic autocorrelation at a temperature of 12 K under continuous wave excitation, and a dominating single photon emission is demonstrated to survive up to 50 K. The deterioration of the g(2)(0)-value at elevated temperatures is well understood as the combined eect of reduced signal-to-background ratio and limited time resolution of the setup. This result underlines the great potential of site controlled pyramidal dots as sources of fast polarized single photons.

  • 23.
    Kazakova, O
    et al.
    National Phys Lab, England .
    Burnett, T L.
    National Phys Lab, England .
    Patten, J
    National Phys Lab, England .
    Yang, L
    National Phys Lab, England .
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Epitaxial graphene on SiC(000(1)over-bar): functional electrical microscopy studies and effect of atmosphere2013Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, nr 21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface potential distribution, V-CPD, and evolution of atmospheric adsorbates on few and multiple layers (FLG and MLG) of graphene grown on SiC(000 (1) over bar) substrate have been investigated by electrostatic and Kelvin force microscopy techniques at T = 20-120 degrees C. The change of the surface potential distribution, Delta V-CPD, between FLG and MLG is shown to be temperature dependent. The enhanced Delta V-CPD value at 120 degrees C is associated with desorption of adsorbates at high temperatures and the corresponding change of the carrier balance. The nature of the adsorbates and their evolution with temperature are considered to be related to the process of adsorption and desorption of the atmospheric water on MLG domains. We demonstrate that both the nano- and microscale wettability of the material are strongly dependent on the number of graphene layers.

  • 24.
    Khranovskyy, Volodymyr
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Glushenkov, Alexey M.
    Deakin University, Australia .
    Chen, Y
    Deakin University, Australia .
    Khalid, A
    Trinity Coll Dublin, Ireland .
    Zhang, H
    Trinity Coll Dublin, Ireland .
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Crystal phase engineered quantum wells in ZnO nanowires2013Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, nr 21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the fabrication of quantum wells in ZnO nanowires (NWs) by a crystal phase engineering approach. Basal plane stacking faults (BSFs) in the wurtzite structure can be considered as a minimal segment of zinc blende. Due to the existing band offsets at the wurtzite (WZ)/zinc blende (ZB) material interface, incorporation of a high density of BSFs into ZnO NWs results in type II band alignment. Thus, the BSF structure acts as a quantum well for electrons and a potential barrier for holes in the valence band. We have studied the photoluminescence properties of ZnO NWs containing high concentrations of BSFs in comparison to high-quality ZnO NWs of pure wurtzite structure. It is revealed that BSFs form quantum wells in WZ ZnO nanowires, providing an additional luminescence peak at 3.329 eV at 4 K. The luminescence mechanism is explained as an indirect exciton transition due to the recombination of electrons in the QW conduction band with holes localized near the BSF. The binding energy of electrons is found to be around 100 meV, while the excitons are localized with the binding energy of holes of ~5 meV, due to the coupling of BSFs, which form QW-like structures.

  • 25.
    Khromov, Sergey
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Gregorius, D.
    Institut für Oberflächen- und Schichtanalytik IFOS GmbH, Kaiserslautern, Germany.
    Schiller, R.
    Institut für Oberflächen- und Schichtanalytik IFOS GmbH, Kaiserslautern, Germany.
    Lösch, J.
    Institut für Oberflächen- und Schichtanalytik IFOS GmbH, Kaiserslautern, Germany.
    Wahl, M.
    Institut für Oberflächen- und Schichtanalytik IFOS GmbH, Kaiserslautern, Germany.
    Kopnarski, M.
    Institut für Oberflächen- und Schichtanalytik IFOS GmbH, Kaiserslautern, Germany.
    Amano, A.
    Department of Electrical Engineering and Computer Science, Nagoya University, Chikusaku, Japan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Atom probe tomography study of Mg doped GaN layers2014Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 25, nr 27, s. 275701-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Atom probe tomography studies on highly Mg-doped GaN(0001) layers with concentrations 5×1019 cm-3 and 1×1020 cm-3 were performed. Mg cluster formation was observed only in the higher doped sample whereas in the lower doped sample the Mg distribution was homogeneous. CL measurements showed that the emission normally attributed to stacking faults was only present in the lower doped layers ([Mg] = 1.5×1019 and 5×1019 cm-3), but absent in the higher-doped layer, where Mg clusters were detected. Mg clusters are proposed to produce a screening effect thereby destroying the exciton binding on the SFs thus rendering them optically inactive.

  • 26.
    Klason, P
    et al.
    University of Gothenburg.
    Nour, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Electrical characteristics and stability of gold and palladium Schottky contacts on ZnO nanorods2008Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Nanotechnology, Vol. 19, nr 47, s. 475202-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrical characteristics and stability of Pd and Au Schottky contacts on ZnO nanorods grown on glass substrate have been investigated. The nanorods were grown using the aqueous chemical growth method. The nanorods were characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD) and photoluminescence (PL). Prior to the metal contact deposition, an insulating PMMA layer was deposited between the nanorods. The best-produced Schottky contact was an as-deposited Pd/ ZnO contact with an ideality factor of 1.7 +/- 0.43 and a barrier height of 0.67 +/- 0.09 eV. The relatively high ideality factor indicates that the current transport cannot be described by pure thermionic transport. The presence of surface states due to the high evaporation pressure is probably the reason for the high ideality factor. Post metal deposition annealing at 150 degrees C for 30 min in air lowered the barrier height and decreased the Au/ ZnO ideality factor but increased it for Pd/ ZnO. The current follows ohmic behavior when the applied forward bias, V-forward, is lower than 0.1 V, whereas for Vforward between 0.1 and 0.45 V the current follows I similar to exp(cV), and at higher forward biases the current-voltage characteristics follow the relation I similar to V-2, indicating that the space-charge current-limiting mechanism is dominating the current transport.

  • 27.
    Lundskog, Anders
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Eriksson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 30, s. 305708-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Growing InGaN quantum dots (QDs) at the apex of hexagonal GaN pyramids is an elegant approach to achieve a deterministic positioning of QDs. Despite similar synthesis procedures by metal–organic chemical vapor deposition, the optical properties of the QDs reported in the literature vary drastically. The QDs tend to exhibit either narrow or broad emission lines in the micro-photoluminescence spectra. By coupled microstructural and optical investigations, the QDs giving rise to narrow emission lines were concluded to nucleate in association with a (0001) facet at the apex of the GaN pyramid.

  • 28.
    Macucci, M.
    et al.
    Dipartimento di Ingegneria dell'Informazione, Università di Pisa, Via Diotisalvi, 2 I-56126 Pisa, Italy.
    Iannaccone, G.
    Dipartimento di Ingegneria dell'Informazione, Università di Pisa, Via Diotisalvi, 2 I-56126 Pisa, Italy.
    Greer, J.
    National Microelectronics Research Center, Lee Maltings, Cork, Ireland.
    Martorell, J.
    Departament d'Estructura I Constituents de la Materia, Facultat de Física, Universitat de Barcelona, E-08028 Barcelona, Spain.
    Sprung, D.W.L.
    Department of Physics and Astronomy, McMaster University, Hamilton, Ont., Canada.
    Schenk, A.
    Swiss Federal Institute of Technology, Integrated Systems Laboratory, Gloriastrasse 35, CH-8092, Zürich, Switzerland.
    Yakimenko, I.I.
    Berggren, Karl-Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Stokbro, K.
    MIC-Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
    Gippius, N.
    General Physics Institute, RAS Vasilova 38, 117333 Moscow, Russian Federation.
    Status and perspectives of nanoscale device modelling2001Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 12, nr 2, s. 136-142Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    During the meetings of the theory and modelling working group, within the MEL-ARI (Microelectronics Advanced Research Initiative) and NID-FET (Nanotechnology Information Devices-Future and Emerging Technologies) initiatives of the European Commission, we have been discussing the current status and the future perspectives of nanoscale device modelling. The outcome of such a discussion is summarized in the present paper, outlining the major challenges for the future, such as the integration of nonequilibrium phenomena and of molecular-scale properties. We believe that modelling has a growing importance in the development of nanoelectronic devices and must therefore make a move from physics to engineering, providing valid design tools, with quantitative predictive capabilities.

  • 29.
    Mazzotta, Francesco
    et al.
    Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-41296, Gothenburg, Sweden.
    Hook, Fredrik
    Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-41296, Gothenburg, Sweden.
    Jonsson, Magnus P.
    Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-41296, Gothenburg, Sweden.
    High throughput fabrication of plasmonic nanostructures in nanofluidic pores for biosensing applications2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 41, artikkel-id 415304Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the primary advantages of nanoscale sensors is that they often can provide conceptually new ways of performing sensing that are not feasible with their large-scale analogs. For example, the small size of nanoscale sensor elements, such as plasmonic metal nanoparticles, allows them to be combined with nanofluidic systems. Among the potential applications of such a combination is the efficient delivery of analyte to the sensor surface. With this in mind, in this work we look to address the challenge of creating and positioning nanoplasmonic sensor elements within nanofluidic pores. A scheme is presented that allows for the production of arrays of pores in a thin (220 nm) silicon nitride membrane with one plasmonic nanoparticle sensor element in each pore. The high throughput fabrication protocol is parallel and enables multiple sensor chips to be produced simultaneously, yet with accurate tuning of the dimension and shape of the nanoparticles. The presented system is shown to possess polarization-sensitive plasmonic resonances that can be tuned significantly in the visible wavelength range by just varying one process parameter. The thickness of the membrane could be optimized to minimize the influence of the optical membrane interference on the plasmonic readout. The sensitivity of the plasmon resonances to changes in refractive index, which forms the basis for using the system for biosensing, was found to be competitive with other nanoplasmonic sensors.

  • 30.
    Moskalenko, Evgenii
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Larsson, Arvid
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Spin polarization of neutral excitons in quantum dots: the role of the carrier collection area2010Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, NANOTECHNOLOGY, Vol. 21, nr 34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high degree (approximate to 55%) of circular polarization has been observed for the neutral exciton in InAs/GaAs quantum dots (QDs). The possibility to record non- zero polarization of the neutral exciton is explained in terms of different capture times of the light electron compared with the heavier holes into the QDs from the wetting layer. This interpretation is supported by the progressive reduction of the polarization degree with increasing QD density, and also with increasing temperature.

  • 31.
    Nyberg, Tobias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Zhang, Fengling
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Inganäs, Olle
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik.
    Submicrometre bridge electrode arrays for light emitting polymer diodes and photodiodes2002Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 13, nr 2, s. 205-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have used a method of soft lithography, soft imprinting, to fabricate submicrometre structures to be used as light emitting polymer diodes and photodiodes. Using a silicone rubber replica (stamp) of an optical diffraction grating we transferred the grating pattern to an organic resist layer by placing the stamp in conformal contact with the resist. The transferred pattern was subsequently used as an etch mask for the processing of the device. This cheap and fast process, not limited by optical diffraction, was used to fabricate submicrometre structures over large areas, square millimetres. The structures were successfully utilized as light emitting diodes and photodiodes, with device characteristics influenced by the imposed structure.

  • 32.
    Palisaitis, Justinas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Core-shell formation in self-induced InAlN nanorods2017Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, nr 11, artikkel-id 115602Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have examined the early stages of self-induced InAlN core-shell nanorod (NR) formation processes on amorphous carbon substrates in plan-view geometry by means of transmission electron microscopy methods. The results show that the grown structure phase separates during the initial moments of deposition into a majority of Al-rich InAlN and a minority of In-enriched InAlN islands. The islands possess polygonal shapes and are mainly oriented along a crystallographic c-axis. The growth proceeds with densification and coalescence of the In-enriched islands, resulting in a base for the In-enriched NR cores with shape transformation to hexagonal. The Al-rich shell formation around such early cores is observed at this stage. The matured core-shell structure grows axially and radially, eventually reaching a steady growth state which is dominated by the axial NR growth. We discuss the NR formation mechanism by considering the adatom surface kinetics, island surface energy, phase separation of InAlN alloys, and incoming flux directions during dual magnetron sputter epitaxy.

  • 33.
    Rawat, P K.
    et al.
    Indian Institute Technology, India .
    Paul, B
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Banerji, P
    Indian Institute Technology, India .
    Thermoelectric properties of PbSe0.5Te0.5: x (PbI2) with endotaxial nanostructures: a promising n-type thermoelectric material2013Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, nr 21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present investigation, we report on the thermoelectric properties of PbSe0.5Te0.5: x (PbI2) from room temperature to 625 K. High-resolution transmission electron micrographs of the samples reveal endotaxial nanostructures embedded in a PbSe0.5Te0.5 matrix. The combined effect of mass fluctuation and nanostructures reduces the thermal conductivity to a great extent compared to PbTe and PbSe, without affecting the carrier mobility. As a result, a thermoelectric figure of merit with a value of 1.5 is achieved at 625 K. This value is significantly higher than that of the available state-of-the-art n-type materials.

  • 34.
    Ren, Qijun
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Filippov, Stanislav
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Chen, Shula
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Evidence for coupling between exciton emissions and surface plasmon in Ni-coated ZnO nanowires2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 42, s. 425201-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show that coating ZnO nanowires (NWs) with a transition metal, such as Ni, can increase the efficiency of light emission at room temperature. Based on detailed structural and optical studies, this enhancement is attributed to energy transfer between near-band-edge emission in ZnO and surface plasmons in the Ni film which leads to an increased rate of the spontaneous emission. It is also shown that the Ni coating leads to an enhanced non-radiative recombination via surface states, which becomes increasingly important at low measurement temperatures and in annealed ZnO/Ni NWs.

  • 35.
    Riaz, M.
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Fulati, Alimujiang
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Zhao, Qingxiang
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Nour, Omer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Willander, Magnus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Klason, P.
    Department of Physics, Göteborg University, SE-41296 Göteborg, Sweden.
    Buckling and mechanical instability of ZnO nanorods grown on different substrates under uniaxial compression2008Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Nanotechnology, Vol. 19, nr 41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (a-Al2O3) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al2O3 substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al2O3 substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10-12, 1.158 × 10-11 and 1.092 × 10-11 J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate. © IOP Publishing Ltd.

  • 36.
    Satti Osman, Eiman
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Chey, Chan Oeurn
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    A flexible anisotropic self-powered piezoelectric direction sensor based on double sided ZnO nanowires configuration2015Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 9, artikkel-id 095502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have successfully synthesized highly dense and well aligned zinc oxide nanowires (NWs) on the two sides of a PEDOT: PSS substrate by a single step low temperature hydrothermal method. The grown sample was used to fabricate a double sided piezoelectric nanogenerator (NG). The maximum harvested output power density from the fabricated double sided NG configuration was about 4.44 mW cm(-2). The results obtained from the present double sided NG were approximately double the output from a single side. In addition to that, the voltage polarity of the harvested voltage from the two sides of the NG has been investigated. The results showed that upon bending, an anisotropic voltage polarity is generated on the two sides. Indicating that, this double sided NG can be used as a self-powered voltage polarity based direction sensor. The results of the present flexible double sided NG is very promising for harvesting energy from irregular mechanical energy sources in the surrounding environment. In addition, the fabricated configuration showed stability for sensing and can be used in surveillance and security applications.

  • 37.
    Savoyant, A.
    et al.
    Aix Marseille University, France.
    Alnoor, Hatim
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Pilone, O.
    Aix Marseille University, France.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Core-defect reduction in ZnO nanorods by cobalt incorporation2017Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, nr 28, artikkel-id 285705Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 38.
    Serban, Alexandra
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Poenaru, Iuliana
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Junaid, Junaid
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy2015Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 21, s. 215602-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Catalystless growth of InxAl1-xN core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl1-xN nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl1-xN film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl1-xN is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl1-xN[0001]//Si[111] and InxAl1-xN[11 (2) over bar0]//Si[1 (1) over bar0] by removing the native SiOx layer from the substrate.

  • 39.
    Shtepliuk, Ivan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Interaction of epitaxial graphene with heavy metals: towards novel sensing platform2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 29, artikkel-id 294002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Development of next-generation sensors based on graphene materials, especially epitaxial graphene (EG) as the most promising representative, with desirable cross-reactivity to heavy metals (HMs) is of great technological significance in the virtue of enormous impact on environmental sensorics. Nevertheless, the mechanisms by which EG responds to toxic HMs exposure and then produces the output signal are still obscure. In the present study, the nature of interaction of toxic HMs, e.g. Cd, Hg and Pb in neutral charge state and EG on Si-face SiC in the absence and in the presence of pure water solution has been investigated using density functional theory with the inclusion of dispersion correction and cluster model of EG. The gas-phase calculations showed that adsorbed electron-donating Cd and Hg adatoms on EG are most stable when bonded to hollow sites, while Pb species prefer to sit above bridge sites. By using non-covalent interaction analysis, charge decomposition analysis, overlap population density of states analysis and topological analysis, it was found that the interaction between Cd or Hg and EG is non-bonding in nature and is mainly governed by van der Waals forces, while Pb adsorption is followed by the formation of anti-bonding orbitals in vacuum conditions and bonding orbitals in water. The role of solvent in the adsorption behavior of HMs is studied and discussed. The present theoretical analysis is in good agreement with recent experimental results towards discriminative electrochemical analysis of the toxic HMs in aqueous solutions at critically low concentrations.

  • 40.
    Stehr, Jan Eric
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska fakulteten.
    Chen, Shula
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Filippov, Stanislav
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska fakulteten.
    Devika, M
    Gwangju Institute Science and Technology, South Korea .
    Koteeswara Reddy, N
    Gwangju Institute Science and Technology, South Korea .
    Tu, C W
    Gwangju Institute Science and Technology, South Korea University of Calif San Diego, CA 92093 USA .
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Defect properties of ZnO nanowires revealed from an optically detected magnetic resonance study2013Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, nr 1, s. 015701-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optically detected magnetic resonance (ODMR) complemented by photoluminescence measurements is used to evaluate optical and defect properties of ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition. By monitoring visible emissions, several grown-in defects are revealed and attributed to Zn vacancies, shallow (but not effective mass) donor and exchange-coupled pairs of Zn vacancies and Zn interstitials. It is also found that the intensity of the donor-related ODMR signals is substantially lower in the NWs compared with that in bulk ZnO. This may indicate that formation of native donors is suppressed in NWs, which is beneficial for achieving p-type conductivity.

  • 41.
    Tripathi, J. K.
    et al.
    Tel Aviv University, Israel; Tel Aviv University, Israel.
    Garbrecht, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kaplan, W. D.
    Technion Israel Institute Technology, Israel.
    Markovich, G.
    Tel Aviv University, Israel; Tel Aviv University, Israel.
    Goldfarb, I.
    Tel Aviv University, Israel; Tel Aviv University, Israel; Tel Aviv University, Israel.
    The effect of Fe-coverage on the structure, morphology and magnetic properties of alpha-FeSi2 nanoislands2012Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, nr 49, artikkel-id 495603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Self-assembled alpha-FeSi2 nanoislands were formed using solid-phase epitaxy of low (similar to 1.2 ML) and high (similar to 21 ML) Fe coverages onto vicinal Si(111) surfaces followed by thermal annealing. At a resulting low Fe-covered Si(111) surface, we observed in situ, by real-time scanning tunneling microscopy and surface electron diffraction, the entire sequence of Fe-silicide formation and transformation from the initially two-dimensional (2 x 2)-reconstructed layer at 300 degrees C into (2 x 2)-reconstructed nanoislands decorating the vicinal step-bunch edges in a self-ordered fashion at higher temperatures. In contrast, the silicide nanoislands at a high Fe-covered surface were noticeably larger, more three-dimensional, and randomly distributed all over the surface. Ex situ x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy indicated the formation of an alpha-FeSi2 island phase, in an alpha-FeSi2{112} parallel to Si{111} orientation. Superconducting quantum interference device magnetometry showed considerable superparamagnetism, with similar to 1.9 mu B/Fe atom at 4 K for the low Fe-coverage, indicating stronger ferromagnetic coupling of individual magnetic moments, as compared to high Fe-coverage, where the calculated moments were only similar to 0.8 mu B/Fe atom. Such anomalous magnetic behavior, particularly for the low Fe-coverage case, is radically different from the non-magnetic bulk alpha-FeSi2 phase, and may open new pathways to high-density magnetic memory storage devices.

  • 42.
    Troncale, V.
    et al.
    Ecole Polytech Fed Lausanne.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kapon, E.
    Ecole Polytech Fed Lausanne.
    Dynamic switching of hole character and single photon polarization using the quantum confined Stark effect in quantum dot-in-dot structures2010Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 21, nr 28, s. 285202-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The engineering of the three-dimensional (3D) heterostructure potential in GaAs/AlGaAs pyramidal quantum dot-in-dots (DiDs) provides control over the valence band symmetry and hence on the polarization of the emitted photons. We propose a technique for dynamic switching of hole character and photon polarization in DiDs by means of an applied electric field. The structural parameters required for producing this effect are discussed. Asymmetric DiDs are found to be particularly suitable for obtaining switching with fields smaller than 1 kV cm(-1). The proposed device enables generation of single photons with dynamic control on the photon polarization, with potential applications in quantum information technology.

  • 43.
    Verschueren, Daniel V
    et al.
    Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
    Jonsson, Magnus P
    Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
    Dekker, Cees
    Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
    Temperature dependence of DNA translocations through solid-state nanopores2015Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, s. 1-8, artikkel-id 234004Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to gain a better physical understanding of DNA translocations through solid-state nanopores, we study the temperature dependence of λ-DNA translocations through 10 nm diameter silicon nitride nanopores, both experimentally and theoretically. The measured ionic conductance G, the DNA-induced ionic-conductance blockades [Formula: see text] and the event frequency Γ all increase with increasing temperature while the DNA translocation time τ decreases. G and [Formula: see text] are accurately described when bulk and surface conductances of the nanopore are considered and access resistance is incorporated appropriately. Viscous drag on the untranslocated part of the DNA coil is found to dominate the temperature dependence of the translocation times and the event rate is well described by a balance between diffusion and electrophoretic motion. The good fit between modeled and measured properties of DNA translocations through solid-state nanopores in this first comprehensive temperature study, suggest that our model captures the relevant physics of the process.

  • 44.
    Wadesa, Amal
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Nour, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Willander , Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    The effect of the interlayer design on the electroluminescence and electrical properties of n-ZnO nanorod/p-type blended polymer hybrid light emitting diodes2009Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, nr 6, s. 065710-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 45.
    Yukimune, M.
    et al.
    Ehime Univ, Japan.
    Fujiwara, R.
    Ehime Univ, Japan.
    Mita, T.
    Ehime Univ, Japan.
    Tsuda, N.
    Ehime Univ, Japan.
    Natsui, J.
    Ehime Univ, Japan.
    Shimizu, Y.
    Toray Res Ctr, Japan.
    Jansson, Mattias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Balagula, Roman
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Chen, Weimin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Buyanova, Irina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Ishikawa, F.
    Ehime Univ, Japan.
    Molecular beam epitaxial growth of dilute nitride GaNAs and GaInNAs nanowires2019Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, nr 24, artikkel-id 244002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the growth of dilute nitride GaNAs and GaInNAs core-multishell nanowires (NWs) using molecular beam epitaxy assisted by a plasma source. Using the self-catalyst vapor-liquid-solid growth mode, these NWs were grown on Si(111) and silicon on insulator substrates. The GaNAs and GaInNAs shells contain nitrogen up to 3%. Axial cross-sectional scanning transmission electron microscopy measurements and energy-dispersive x-ray spectrometry confirm the formation of the core-multishell NW structure. We obtained high-quality GaNAs NWs with nitrogen compositions up to 2%. On the other hand, GaNAs containing 3% nitrogen, and GaInNAs NWs, show distorted structures; moreover, the optical emissions seem to be related to defects. Further optimisations of the growth conditions will improve these properties, promising future applications in nanoscale optoelectronics.

    Fulltekst tilgjengelig fra 2020-03-26 11:28
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