physica status solidi (RRL) - Rapid Research Letters

Cover image for Vol. 7 Issue 8

August 2013

Volume 7, Issue 8

Pages 521–594

  1. Cover Picture

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      Cover Picture: Silicene on hydrogen-passivated Si(111) and Ge(111) substrates (Phys. Status Solidi RRL 8/2013)

      Sebastian Kokott, Lars Matthes and Friedhelm Bechstedt

      Article first published online: 13 AUG 2013 | DOI: 10.1002/pssr.201370444

      Thumbnail image of graphical abstract

      Several researchers claim to have produced silicene, the graphene-like allotrope of silicon, that could result in the ultimate miniaturization of the Si-device technology and in novel electronic and optical properties due to the appearance of massless Dirac electrons. It is sometimes described as a new “wonder material”. Favored substrates are Ag(111) and Ir(111) metal surfaces. However, the growth of silicene layers is a huge challenge. Recent theoretical and experimental studies show a destruction of the Dirac cones due to a lowering of the honeycomb symmetry and the strong interaction with the substrate. In the Letter by Kokott, Matthes, and Bechstedt (pp. 538–541) the possibility of the silicene formation on hydrogen-passivated Si(111) (as displayed on the front cover) and Ge(111) surfaces is predicted. The stability of a silicene sheet and its exceptional electronic properties are demonstrated by first-principles studies. The van-der-Waals interaction bonds the silicene layer to the inert substrates. Because of the reduced chemical interaction the linear conical bands near the corner points of the hexagonal Brillouin zone survive with an extremely small energy gap.

  2. Back Cover

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      Back Cover: Enhancing electrooptic modulators using modulation instability (Phys. Status Solidi RRL 8/2013)

      Peter T. S. DeVore, David Borlaug and Bahram Jalali

      Article first published online: 13 AUG 2013 | DOI: 10.1002/pssr.201370445

      Thumbnail image of graphical abstract

      Modulation instability is a universal nonlinear process wherein a weak perturbation grows on an otherwise quiet background. Inspired by recent work on stimulating modulation instability to tame optical rogues waves, DeVore, Borlaug, and Jalali (see their Letter on pp. 566–570) stimulate it with the weak sidebands of an electrooptically modulated carrier. In this process, the sidebands are boosted at the expense of the carrier, which enables low-voltage, high bandwidth modulation, the most pressing need in optical communications. In the cover figure, we see that a traditional optical link weakly transfers high-frequency radio frequency waves, but the fortuitous increase of modulation instability gain with frequency allows transfer of the full bandwidth.

  3. Issue Information

    1. Top of page
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    3. Back Cover
    4. Issue Information
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    6. NEW IN pss
    7. rrl solar
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    1. You have free access to this content
      Issue Information: Phys. Status Solidi RRL 8/2013

      Article first published online: 13 AUG 2013 | DOI: 10.1002/pssr.201370446

  4. Contents

    1. Top of page
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    3. Back Cover
    4. Issue Information
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      Contents: Phys. Status Solidi RRL 8/2013 (pages 521–527)

      Article first published online: 13 AUG 2013 | DOI: 10.1002/pssr.201370447

  5. NEW IN pss

    1. Top of page
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    3. Back Cover
    4. Issue Information
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    6. NEW IN pss
    7. rrl solar
    8. Rapid Research Letters
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    1. You have free access to this content
  6. rrl solar

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    1. Silicon solar cells

      Enhanced rear-side reflection and firing-stable surface passivation of silicon solar cells with capping polymer films (pages 530–533)

      James Bullock, Andrew Thomson, Andrés Cuevas, Boris Veith, Jan Schmidt and Ari Karkkainen

      Article first published online: 14 JUN 2013 | DOI: 10.1002/pssr.201307200

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      Inexpensive protective capping films are applied to the rear-side of silicon solar cell precursors. These films are shown to provide protection to an underlying surface passivation layer during the high-temperature firing process required for contact formation. The low refractive index of these materials also provides enhanced rear-side internal reflection (hence a larger generation current) as compared to a standard SiNx capping.

    2. Hybrid solar cells

      Hybrid polymer/inorganic nanoparticle blended ternary solar cells (pages 534–537)

      Seokhyun Yoon, Seung Jin Heo and Hyun Jae Kim

      Article first published online: 25 JUN 2013 | DOI: 10.1002/pssr.201307157

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      In this Letter, the authors report the effect of PbS quantum dots in a hybrid active layer. By blending PbS quantum dots into the active layer in organic solar cells, the power conversion efficiency of hybrid solar cells was increased. The PbS quantum dots were expanding light absorption and improving charge transport in the hybrid active layer.

  7. Rapid Research Letters

    1. Top of page
    2. Cover Picture
    3. Back Cover
    4. Issue Information
    5. Contents
    6. NEW IN pss
    7. rrl solar
    8. Rapid Research Letters
    9. Information for authors
    1. Silicene

      Silicene on hydrogen-passivated Si(111) and Ge(111) substrates (pages 538–541)

      Sebastian Kokott, Lars Matthes and Friedhelm Bechstedt

      Article first published online: 25 JUN 2013 | DOI: 10.1002/pssr.201307215

      Thumbnail image of graphical abstract

      The growth of silicene, the graphene-like allotrope of silicon, is an unsolved challenge. As a favorable approach the silicene formation on a hydrogenated Si(111) or Ge(111) substrate is predicted. Its stability and electronic properties are demonstrated by first-principles studies.

    2. Electrode–graphene interface

      The effect of electrode/graphene interfaces and dephasing processes on conductance and giant magnetoresistance (pages 542–545)

      S. Krompiewski

      Article first published online: 17 JUN 2013 | DOI: 10.1002/pssr.201307137

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      This Letter explains the impact of graphene/electrode interfaces on spin-dependent electronic transport in the presence of dephasing processes. The emphasis is put on giant magnetoresistance (GMR) of graphene nanoribbons (GNRs) sandwiched between ferromagnetic electrodes. In view of potential spintronic applications of graphene, the following issues are addressed: comparison of end- and side-contacted setups, effect of current flow direction, and relevance of the GNR aspect ratio. It is shown that typically GMR of the zigzag GNR is lower than that of the armchair GNR, and the dephasing mechanisms can increase the GMR at low gate voltages.

    3. Carbon nanotubes

      Selective interaction between nanotubes and perylene-based surfactant (pages 546–549)

      Friederike Ernst, Sebastian Heeg, Timm Heek, Antonio Setaro, Rainer Haag and Stephanie Reich

      Article first published online: 14 JUN 2013 | DOI: 10.1002/pssr.201307221

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      Standard surfactants do not interact with all nanotube chiralities equally well. Certain chiralities, such as the (11,1) tube, remain mostly bundled. Photoluminescence spectra consequently reflect the actual chirality distribution poorly, even after chirality specific coupling to light is taken into account. Organic chromophores can aid the debundling process for these chiralities substantially.

    4. MOSFETs

      Hole mobility and remote scattering in strained InGaSb quantum well MOSFET channels with Al2O3 oxide (pages 550–553)

      Shailesh Kumar Madisetti, Thenappan Chidambaram, Padmaja Nagaiah, Vadim Tokranov, Michael Yakimov and Serge Oktyabrsky

      Article first published online: 25 JUN 2013 | DOI: 10.1002/pssr.201307243

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      This Letter provides the baseline for p-type surface and buried InGaSb quantum well MOSFET channel conductivity and mobility (μ) using the Hall effect. Reducing the top-barrier thickness in burried channel structures from 50 nm to 0 nm drops mobility by ∼30% and the temperature dependence flattens down at sheet density of ∼1012 cm–2 (Fig. (a)). The mobility dependence on temperature and hole density (Fig. (b)) and top barrier thickness is used to analyze the scattering mechanisms.

    5. MgZnO/ZnO heterostructures

      Ultra-low acoustic-phonon-limited mobility and giant phonon-drag thermopower in MgZnO/ZnO heterostructures (pages 554–557)

      Margarita Tsaousidou

      Article first published online: 28 JUN 2013 | DOI: 10.1002/pssr.201307198

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      The acoustic-phonon-limited mobility of two-dimensional electron gases confined in MgZnO/ZnO heterostructures is calculated within the semiclassical Boltzmann framework. Good agreement is obtained with the experiment without adjustable parameters. Interestingly, the calculated magnitude of phonon-drag thermopower exceeds 200 mV/K at T = 5 K resulting in high values of the figure of merit, ZT. ZnO-based two-dimensional systems are suggested to be good thermoelectric materials at cryogenic temperatures.

    6. Organic transistors

      Fabricating organic transistors based on domain-ordered copper phthalocyanine film grown on oligothiophene epitaxial substrate (pages 558–561)

      Yulei Hu, Wen Gu, Na Liu, Zongpeng Zhu, Jianhua Zhang and Jun Wang

      Article first published online: 21 JUN 2013 | DOI: 10.1002/pssr.201307206

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      A copper phthalocyanine (CuPc) thin film was prepared by introducing oligothiophene as the buffer layer. Domain-order structure is then clearly observed that significantly depends on the thickness of oligothiophene. The corresponding field-effect mobility of organic transistors is five times larger than that of devices based on single-layer CuPc.

    7. Plasmonic sensors

      Plasmonic sensors based on thick metal film perforated with rectangular nanohole arrays (pages 562–565)

      Li Yuan and Fuyi Chen

      Article first published online: 21 JUN 2013 | DOI: 10.1002/pssr.201307189

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      In this Letter, the authors report the dependence of optical properties on the ambient medium, the period of nanohole arrays and the metal film thickness in a thick silver film perforated with rectangular nanohole arrays. Based on the interesting optical properties of the thick metal rectangular nanohole arrays as a result of coupling between the top and down surface plasmon polaritons, these arrays are found to present potential application as plasmonic sensors.

    8. Electrooptic modulators

      Enhancing electrooptic modulators using modulation instability (pages 566–570)

      Peter T. S. DeVore, David Borlaug and Bahram Jalali

      Article first published online: 26 JUN 2013 | DOI: 10.1002/pssr.201307174

      Thumbnail image of graphical abstract

      Modulation instability, the origin of optical rogue waves, is a universal nonlinear process wherein a weak perturbation grows on an otherwise quiet background. Here, the authors exploit optical modulation instability to boost weak sidebands of electrooptic modulators, laying a path to solving the most pressing problem in optical communications: low-voltage, high-bandwidth modulation.

    9. Scintillators

      Gd3+ to Ce3+ energy transfer in multi-component GdLuAG and GdYAG garnet scintillators (pages 571–574)

      Miroslav Kučera, Martin Nikl, Martin Hanuš and Zuzana Onderišinová

      Article first published online: 21 JUN 2013 | DOI: 10.1002/pssr.201307256

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      The authors have explored experimentally the energy transfer from Gd3+ to Ce3+ ions in single-crystalline garnet scintillators. While at low concentrations, the isolated Gd3+ ions are very efficient but slow emitters, at higher concentrations these ions can serve as donors and transfer excitation energy to Ce3+ activators. High scintillation efficiency of Ce3+ doped garnets is thus mediated by the Gd sublattice and the energy migration over the Gd ions in Gd-concentrated systems further enhances the nonradiative energy transfer towards the Ce3+ centers.

    10. Dielectric permittivity

      Enhanced dielectric permittivity of fluorine polyimide matrix with embedded graphene (pages 575–578)

      Jingni Liu, Jingda Song, Shengli Qi, Guofeng Tian and Dezhen Wu

      Article first published online: 25 JUN 2013 | DOI: 10.1002/pssr.201307193

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      This Letter investigates the dielectric properties of nanohybrid materials fabricated by using an electroactive polyimide 6FDA/ODA containing fluorine as matrix and graphene as conductive fillers. The derived materials exhibit significant increases in the dielectric permittivity, which is explained by the percolation theory, microcapacitor model and the electron donor–acceptor effect.

    11. Graphene quantum dots

      A graphene quantum dot realized by an armchair graphene nanoribbon with line defect (pages 579–582)

      Xiao-Yan Sui, Zhi-Chao Li, Wei-Jiang Gong, Guo-Dong Yu and Xiao-Hui Chen

      Article first published online: 26 JUN 2013 | DOI: 10.1002/pssr.201307152

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      This Letter investigates the electron transport in a semiconducting armchair graphene nanoribbon which is coupled to two normal metallic leads. It is found that the line defect embedded in the nanoribbon induces a localized quantum state near the Dirac point which contributes to the resonant tunneling. So, such a finite-size nanoribbon can be viewed as a quantum dot, and such a structure can be considered to be a promising candidate for the electron manipulation in graphene.

    12. Half-metallic perovskites

      Coulomb-enhanced spin–orbit coupling and semiconductor to half-metal transition under pressure in Sr2CrReO6 (pages 583–586)

      Jing Wang, Ningning Zu, Ying Wang and Zhijian Wu

      Article first published online: 26 JUN 2013 | DOI: 10.1002/pssr.201307207

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      Semiconducting behavior of Sr2CrReO6 can only be reproduced by considering both electron correlation and spin–orbit coupling simultaneously with large electron correlation of rhenium (≤5.0 eV). The calculated band gap is 0.22 eV, close to the experimental value of 0.21 eV. By applying pressure, a semiconductor to half-metal transition is observed at 12.6 GPa.

    13. Epitaxial ZnO

      Growth of epitaxial c -plane ZnO film on a -plane sapphire by radio frequency reactive magnetron sputtering (pages 587–589)

      Hongyan Liu, Shuang Gao, Fei Zeng, Cheng Song and Feng Pan

      Article first published online: 25 JUN 2013 | DOI: 10.1002/pssr.201307197

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      The growth of single domain epitaxial c -plane ZnO films on a -plane sapphire substrates is carried out for the first time by using radio frequency reactive magnetron sputtering. A new method for the measurement of the defect density in ZnO films is proposed in terms of the relationship between photoluminescence and defect density.

    14. Interface formation

      High-resolution photoemission comparison study of interface formation between MgO and the atomically clean and Se-passivated Ge(100) surfaces (pages 590–592)

      Rajesh Kumar Chellappan and Greg Hughes

      Article first published online: 20 JUN 2013 | DOI: 10.1002/pssr.201307170

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      In this Letter, the interface formation between MgO dielectric layers and the atomically clean and selenium-passivated Ge(100) surfaces has been studied using high-resolution synchrotron radiation based soft X-ray photoelectron spectroscopy. The Ge 3d spectra acquired at 60 eV for the MgO/Se/Ge sample show the effectiveness of selenium passivated germanium surface at preventing interfacial oxidation during MgO deposition.

  8. Information for authors

    1. Top of page
    2. Cover Picture
    3. Back Cover
    4. Issue Information
    5. Contents
    6. NEW IN pss
    7. rrl solar
    8. Rapid Research Letters
    9. Information for authors
    1. You have free access to this content
      Information for authors: Phys. Status Solidi RRL 8/2013 (pages 593–594)

      Article first published online: 13 AUG 2013 | DOI: 10.1002/pssr.201370449

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