physica status solidi (RRL) - Rapid Research Letters

Cover image for Vol. 6 Issue 9‐10

October 2012

Volume 6, Issue 9-10

Pages A95–A106, 359–414

  1. Cover Picture

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    7. Review@RRL
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      Cover Picture: Non-polar group-III nitride semiconductor surfaces (Phys. Status Solidi RRL 9–10/2012)

      Holger Eisele and Philipp Ebert

      Article first published online: 4 OCT 2012 | DOI: 10.1002/pssr.201290022

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      Non-polar surfaces of compound semiconductor materials are typically characterized by their low surface energies and charge neutrality. But the energetic positions of surface states are crucially determining the properties of a surface, especially during growth and within device applications. In order to reduce discontinuities of the polarization fields in GaN-based heterostructure device applications the switching to non-polar growth surfaces might be a reasonable solution. Furthermore, facets of nanostructured objects, such as e.g., semiconductor nanowires, are most likely formed by non-polar surfaces due to their low surface energy. In the Review@RRL by Holger Eisele and Philipp Ebert (pp. 359–369) the basic properties of group-III nitride semiconductor surfaces are reviewed up to their present knowledge. Based on the structural properties of these surfaces the electronic structure is discussed in comparison between theoretical calculations and experimental results. Particular attention is paid to the question of the energetic position of surface states and the Fermi level position with respect to the fundamental bulk band gap. When investigating these surfaces experimentally, the surface pinning is found to be a crucial effect, on which special attention has to be laid. Beside the intrinsic properties also extrinsic influences on these surfaces are reported, such as defects, adsorbents, and decomposition effects. Last but not least, doping-related effects at these surfaces are discussed.

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      Issue Information: Phys. Status Solidi RRL 9–10/2012

      Article first published online: 4 OCT 2012 | DOI: 10.1002/pssr.201290023

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      Back Cover: Suppression of short-range scattering via hydrophobic substrates and the fractional quantum Hall effect in graphene (Phys. Status Solidi RRL 9–10/2012)

      Stefan Hansel, Myrsini Lafkioti and Vojislav Krstić

      Article first published online: 4 OCT 2012 | DOI: 10.1002/pssr.201290024

      Thumbnail image of graphical abstract

      Being an all-surface material, the transport properties of graphene are altered by a wide range of interactions with the environment. These interactions can originate from molecular and atomic species adsorbed from the atmosphere on the graphene or from the presence of a specific substrate surface. Such interactions can lead to an unintentional doping but more crucially introduce a variety of chargecarrier scattering centres such as charged impurities, lattice strain or resonant scatterers. Hansel, Lafkioti and Krstic´ (see their Letter on pp. 376–378) report on the development of the fractional quantum Hall state with the filling factor 4/3 in graphene on hydrophobically rendered SiO2 surfaces at 4.2 K. The study demonstrates that this physically fundamental manybody state can be realised by strongly suppressing shortrange scattering due to the elimination of localised charged scatterers usually induced by a bare SiO2 surface in contact with graphene. Specifically, the study reveals that upon reduction of charged scatterers the increase of the ratio of meanfree path to chargecarrier separation prevails over the generally believed necessity for an extraordinarily high overall mobility to enable the formation of fractional quantum Hall states in graphene and, thus, provides new insight in the development of the fractional quantum Hall state in relativistic fermion systems.

  4. Contents

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    3. Issue Information
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      Contents: Phys. Status Solidi RRL 9–10/2012 (pages A95–A101)

      Article first published online: 4 OCT 2012 | DOI: 10.1002/pssr.201250428

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  6. Review@RRL

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      Non-polar group-III nitride semiconductor surfaces (pages 359–369)

      Holger Eisele and Philipp Ebert

      Article first published online: 7 SEP 2012 | DOI: 10.1002/pssr.201206309

      Thumbnail image of graphical abstract

      Non-polar surfaces of group-III nitride semiconductors have attracted much attention during the past years. On the one hand, using them as growth surface might reduce discontinuities of the piezoelectric polarization in heterostructures for nitride-based light emitting and laser devices. On the other hand, the major fraction of III-V semiconductor nanowires are confined by non-polar surfaces. In this Letter, the authors review the basic structural and electronic properties of state-of-the-art non-polar group-III nitride surfaces.

  7. Rapid Research Letters

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    1. Role of phosphorus in contact formation on silicon solar cells (pages 370–372)

      Gordana Kulushich, Renate Zapf-Gottwick, Viet X. Nguyen and Jürgen H. Werner

      Article first published online: 31 AUG 2012 | DOI: 10.1002/pssr.201206298

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      The authors of this RRL reveal that the inactive phosphorus at the surface of a solar cell emitter plays a crucial role in the contact formation between the n-type emitter and an industrially screen-printed silver paste. Inactive phosphorus atoms support nucleation and growth of silver crystallites into the emitter by leaving the silicon lattice and forming an alloy of Ag/P within the silver crystallites.

    2. A route to ultrathin quantum gases at polar perovskite heterointerfaces (pages 373–375)

      S. Nazir and U. Schwingenschlögl

      Article first published online: 7 SEP 2012 | DOI: 10.1002/pssr.201206354

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      Nazir and Schwingenschlögl demonstrate a strong confinement of the hole gas at the heterointerface between AgNbO3 and SrTiO3, and attribute the effect to the introduction of electronegative Ag cations. Electronegative cations, in general, appear to be a promising way to enhance the quantum nature of hole gases formed at perovskite heterointerfaces.

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      Suppression of short-range scattering via hydrophobic substrates and the fractional quantum Hall effect in graphene (pages 376–378)

      Stefan Hansel, Myrsini Lafkioti and Vojislav Krstić

      Article first published online: 30 AUG 2012 | DOI: 10.1002/pssr.201206297

      Thumbnail image of graphical abstract

      As an all-surface material, graphene's electronic properties are very susceptible to any type of external influences, such as substrate interactions. However, these interactions can probe the physics of fundamental magneto-induced many-body states in graphene. The fractional quantum Hall state with the filling factor 4/3 in non-suspended graphene is realised at 4.2 K by suppressing substrate-induced short-range scatterers via substrate hydrophobisation. This demonstrates the prevalence of an increased ratio of mean free path to charge carrier separation over extraordinarily high mobility needs.

    4. One-step synthesis of a highly conductive graphene–polypyrrole nanofiber composite using a redox reaction and its use in gas sensors (pages 379–381)

      Huynh Ngoc Tien and Seung Hyun Hur

      Article first published online: 7 SEP 2012 | DOI: 10.1002/pssr.201206333

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      A highly sensitive NO2 sensor composed of a reduced graphene oxide (RGO) and polypyrrole (PPY) nanofiber was fabricated by a one-step redox reaction under UV illumination at room temperature. In this process, electrons generated during pyrrole polymerization convert graphite oxide (GO) to RGO without any reducing agents. Moreover, fibrous PPY was obtained only when GO was used together with pyrrole.

    5. High-pressure optical absorption studies of double-walled carbon nanotubes (pages 382–384)

      Jesús Marquina, Enmanuel Flahaut and Jesús González

      Article first published online: 23 AUG 2012 | DOI: 10.1002/pssr.201206280

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      In this Letter, Marquina et al. report measurements of optical transitions of double-walled carbon nanotubes (DWCNTs) under hydrostatic pressure. The optical transitions were found to be linearly decreased with increasing hydrostatic pressure by about –1.8 meV/kbar. A red-shift as large as 0.2 eV was observed. This study confirms that the DWCNTs are potential candidates for the fabrication of composite nanomaterials for high-load mechanical support because the collapse pressure is higher than for single-walled carbon nanotubes.

    6. Mesoporous and hierarchical manganese dioxide nanoplates/nanowalls on Ni/PET conductive fabric (pages 385–387)

      Yeong Hwan Ko, Soo Hyun Lee and Jae Su Yu

      Article first published online: 5 SEP 2012 | DOI: 10.1002/pssr.201206331

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      Hexagonal MnO2 nanoplates were successfully integrated into the Ni/PET conductive fabric via a simple electrochemical deposition (ED) method. At a proper external cathodic voltage, such nanostructures were well organized on a seed-layer-coated conductive fabric (CF) in aqueous solution, and covered densely and uniformly over the overall surface of the CF. Additionally, by reacting with hydrogen peroxide, they changed to nanowall-like shapes with a more mesoporous and hierarchical morphology.

    7. Towards a better understanding of intergranular phases in Fe–Nd–B sintered magnets (pages 388–390)

      Dagmar Goll, Stephanie Schweizer, Christian Wegierski and Gerhard Schneider

      Article first published online: 29 AUG 2012 | DOI: 10.1002/pssr.201206293

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      To better understand the microstructure of the Nd-rich grain boundary phase in Fe-Nd-B sintered magnets and its influence on the improvement of the magnetic properties during post-sintering annealing, the microstructure has been coarsened in a model experiment to study thermodynamics and kinetics of the intergranular regions under real processing conditions.

    8. Surface-modulated magnetization of magnetite microspheres (pages 391–393)

      Ji Ma and Kezheng Chen

      Article first published online: 27 AUG 2012 | DOI: 10.1002/pssr.201206292

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      The authors of this Letter propose an effectual solution to enhance the magnetic response of surface-coated magnetite microspheres by inducing large lattice strain in magnetic microspheres with silver. The saturation magnetization was found to be larger than that of their parent magnetite spheres at 300 K. More strikingly, an increment of saturation magnetization with temperature was also observed, which has not been reported before in ferrimagnetic systems.

    9. Microwave-induced off-resonance giant magnetoresistance in ultraclean two-dimensional electron systems (pages 394–396)

      J. Iñarrea

      Article first published online: 5 SEP 2012 | DOI: 10.1002/pssr.201206311

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      In this Letter, the authors explain the physics behind the striking off-resonance magnetoresistance spike recently obtained in irradiated two-dimensional electron systems. Key are the narrow Landau levels that show up in ultraclean samples (high mobility). These Landau levels are well-separated, affecting dramatically the electron–impurity scattering, and eventually the measured resistance.

    10. Large dielectric tunability in Na0.5Bi0.5TiO3x %BaTiO3 single crystals (pages 397–399)

      Wenwei Ge, Chengtao Luo, Qinhui Zhang, Jiefang Li, Haosu Luo and D. Viehland

      Article first published online: 23 AUG 2012 | DOI: 10.1002/pssr.201206282

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      In this Letter, the authors describe the performance of electric field dependent dielectric and X-ray diffraction measurements on 〈001〉- and 〈110〉-oriented lead-free piezoelectric Na0.5Bi0.5TiO3–5.6%BaTiO3 single crystals. Dielectric tunability as high as 58% and 46% was obtained at room temperature under an electric field of E = 20 kV/cm applied along [001] and [110].

    11. High-performance solution-processed amorphous ZrInZnO thin-film transistors (pages 400–402)

      Ya-Wei Chung, Fang-Chung Chen, Ying-Ping Chen, Yu-Ze Chen and Yu-Lun Chueh

      Article first published online: 31 AUG 2012 | DOI: 10.1002/pssr.201206323

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      In this Letter, the authors report the preparation of ZrInZnO thin-film transistors with various Zr molar ratios through a simple solution process. The best device exhibits a field effect mobility of 3.80 cm2/Vs and an on–off ratio of ∼107. The Zr element behaves as an effective carrier suppressor, and the presence of Zr atoms also inhibits the crystal growth of the In2O3 phase.

    12. High reliability amorphous oxide semiconductor thin-film transistors gated by buried thick aluminum (pages 403–405)

      Dongxiang Luo, Linfeng Lan, Miao Xu, Hua Xu, Min Li, Jianhua Zou, Hong Tao, Lei Wang and Junbiao Peng

      Article first published online: 20 AUG 2012 | DOI: 10.1002/pssr.201206303

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      In this Letter, an indium-zinc-oxide thin-film transistor (IZO-TFT) with a 1500 nm thick aluminium gate is demonstrated. The Al gate assembly was planarized by a photoresist, and then was further anodized to form a layer of Al2O3 as gate dielectric. The thick Al has low-hillock density and low resistance. This IZO-TFT shows high mobility, high reliability and good electrical stability.

    13. Deposition of gold nanoparticle films using spray pyrolysis technique: Tunability of SPR band by electric field (pages 406–408)

      Neetesh Kumar, Vamsi K. Komarala and Viresh Dutta

      Article first published online: 21 AUG 2012 | DOI: 10.1002/pssr.201206308

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      This Letter reports the fabrication of gold nanoparticle films with tuned surface plasmon resonance (SPR) band positions and bandwidths using an electrostatic force additionally applied to the spray generated droplets. A consistent reduction in droplet size with stepwise increase in electrostatic force due to Coulomb fission overcomes the surface tension of the droplets and leads to a fine aerosol which is clearly reflected by a stepwise reduction of the half-width and blue shift of the SPR band.

    14. Optical switching patterns using electrospun nanofiber array (pages 409–411)

      Bumjoo Kim, Seong J. Cho, Taechang An, Hyobong Ryu, Hoon Lim and Geunbae Lim

      Article first published online: 31 AUG 2012 | DOI: 10.1002/pssr.201206326

      Thumbnail image of graphical abstract

      This Letter reports on the unique reflective behavior of electrospun nanofibers changing the incident light direction. Nanofibers aligned perpendicular to the incoming light are clearly visible, while those aligned parallel to the incoming light are invisible, so-called diffuse and specular reflection, respectively. This critical phenomenon is mainly due to the cylindrical surface of the fibers, and dominates when the fiber becomes smaller, especially on the submicron scale.

    15. Synthesis and luminescence properties of Li2BaSiO4:Eu3+ phosphors (pages 412–414)

      Mubiao Xie and Caiyan Luo

      Article first published online: 4 SEP 2012 | DOI: 10.1002/pssr.201206316

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      Luminescence efficiency, color purity, and decay time are important luminescent characteristics for white light-emitting diode (w-LEDs) phosphors. Xie and Luo study the photoluminescence properties of novel red phosphors Li2–xBa1–x EuxSiO4. They have found that Li1.88Ba0.88Eu0.12SiO4 can be effectively excited by near-ultraviolet light (∼393 nm). It shows an intense red emission (∼ 615 nm), with chromaticity coordinates (0.639, 0.359). The authors consider that these phosphors may be a potential candidate for near-UV w-LEDs.

  8. Information for authors

    1. Top of page
    2. Cover Picture
    3. Issue Information
    4. Back Cover
    5. Contents
    6. NEW IN pss
    7. Review@RRL
    8. Rapid Research Letters
    9. Information for authors
    1. You have free access to this content

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