Applied Physics Letters: All Topics

Indium incorporation and emission properties of nonpolar and semipolar InGaN quantum wells

Yuji Zhao, Qimin Yan, Chia-Yen Huang, Shih-Chieh Huang, Po Shan Hsu et al.
We report indium incorporation properties on various nonpolar and semipolar free-standing GaN substrates. Electroluminescence characterization and x-ray diffraction (XRD) analysis indicate that the semipolar (20[overline 2][overline 1]) and (11[overline 2]2) planes have the highest indium incorporat ... [Appl. Phys. Lett. 100, 201108 (2012)] published Wed May 16, 2012.

Publisher's Note: Field modulation of the electronic structure of trilayer graphene [Appl. Phys. Lett. 98, 263107 (2011)]

Bi-Ru Wu
Abstract not available. [Appl. Phys. Lett. 100, 209901 (2012)] published Wed May 16, 2012.

Aharonov-Bohm effect in an electron-hole graphene ring system

D. Smirnov, H. Schmidt, and R. J. Haug
Aharonov-Bohm oscillations are observed in a graphene quantum ring with a topgate covering one arm of the ring. As graphene is a gapless semiconductor, this geometry allows to study not only the quantum interference of electrons with electrons or holes with holes, but also the unique situation of qu ... [Appl. Phys. Lett. 100, 203114 (2012)] published Wed May 16, 2012.

Relaxor behaviour of KBiNbO-BiScO ceramics

Chatchai Kruea-In, Gobwute Rujijanagul, Fang Yuan Zhu, and Steven J. Milne
Dielectric properties of (1 x)KBiTiO xBiScO ceramics have been studied for compositions x <= 0.5. Single-phase solid solutions occurred for compositions x < 0.25. A frequency-dependent dielectric relaxation was observed, consistent with relaxor behaviour. This gave rise to a relatively stable diel ... [Appl. Phys. Lett. 100, 202904 (2012)] published Wed May 16, 2012.

Phononic bandgaps in graphene-based materials

Michael M. Sigalas and Emmanuel N. Koukaras
The phonon density of states of graphene based materials have been studied using density functional theory. Substitution of the carbon atoms with carbon isotopes may result in the appearance of gaps in the phonon density of states. Wider gaps are introduced when selected carbon atoms are replaced wi ... [Appl. Phys. Lett. 100, 203109 (2012)] published Wed May 16, 2012.

Formation and transformation of embedded GaN nanocrystals

A. W. Wood, R. R. Collino, P. T. Wang, Y. Q. Wang, and R. S. Goldman
We have investigated the nucleation, growth and transformation of nitride nanostructures synthesized by nitrogen ion implantation into GaAs, followed by thermal annealing. High energy implantation into GaAs thin films results in the formation of a nitrogen-rich amorphous layer, with crystalline remn ... [Appl. Phys. Lett. 100, 203113 (2012)] published Wed May 16, 2012.

High performance solution-deposited amorphous indium gallium zinc oxide thin film transistors by oxygen plasma treatment

Pradipta K. Nayak, M. N. Hedhili, Dongkyu Cha, and H. N. Alshareef
Solution-deposited amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) with high performance were fabricated using O-plasma treatment of the films prior to high temperature annealing. The O-plasma treatment resulted in a decrease in oxygen vacancy and residual hydrocarbon conce ... [Appl. Phys. Lett. 100, 202106 (2012)] published Wed May 16, 2012.

Layer-by-layer thermal conductivities of the Group III nitride films in blue/green light emitting diodes

Zonghui Su, Li Huang, Fang Liu, Justin P. Freedman, Lisa M. Porter et al.
Thermal conductivities (k) of the individual layers of a GaN-based light emitting diode (LED) were measured along [0001] using the 3-omega method from 100-400 K. Base layers of AlN, GaN, and InGaN, grown by organometallic vapor phase epitaxy on SiC, have effective k much lower than bulk values. The ... [Appl. Phys. Lett. 100, 201106 (2012)] published Wed May 16, 2012.

Complementary resistive switching in tantalum oxide-based resistive memory devices

Yuchao Yang, Patrick Sheridan, and Wei Lu
Complementary resistive switches (CRS) are considered as a potential solution for the sneak path problem in large-scale integration of passive crossbar resistive memory arrays. A typical CRS is composed of two bipolar memory cells that are connected anti-serially. Here, we report a tantalum-oxide ba ... [Appl. Phys. Lett. 100, 203112 (2012)] published Wed May 16, 2012.

Metamaterial metal-based bolometers

F. B. P. Niesler, J. K. Gansel, S. Fischbach, and M. Wegener
We demonstrate metamaterial metal-based bolometers, which take advantage of resonant absorption in that a spectral and/or polarization filter can be built into the bolometer. Our proof-of-principle gold-nanostructure-based devices operate around 1.5 [mu]m wavelength and exhibit room-temperature time ... [Appl. Phys. Lett. 100, 203508 (2012)] published Wed May 16, 2012.

Anomalous phase change characteristics in Fe-Te materials

X. T. Fu, W. D. Song, H. W. Ho, R. Ji, L. Wang et al.
Phase change materials have become significantly attractive due to its unique characteristics for its extensive applications. In this paper, a kind of phase change material, which consists of Fe and Te components, is developed. The crystallization temperature of the Fe-Te materials is 180 degrees C ... [Appl. Phys. Lett. 100, 201906 (2012)] published Wed May 16, 2012.

Temperature and concentration-dependent relaxation of ferrofluids characterized with a high-T SQUID-based nuclear magnetic resonance spectrometer

Hong-Chang Yang, Chieh-Wen Liu, S. H. Liao, Hsin-Hsien Chen, M. J. Chen et al.
We investigated the relaxation of protons in magnetic fluids using a high-T SQUID magnetometer. It was found that the longitudinal relaxation rate, 1/T, is slower than the transverse relaxation rate, 1/T, for ferrofluids in the same field. This is due to the fact that the 1/T process involves return ... [Appl. Phys. Lett. 100, 202405 (2012)] published Wed May 16, 2012.

Surface passivation of c-Si by atmospheric pressure chemical vapor deposition of AlO

Lachlan E. Black and Keith R. McIntosh
Atmospheric pressure chemical vapor deposition of AlO is shown to provide excellent passivation of crystalline silicon surfaces. Surface passivation, permittivity, and refractive index are investigated before and after annealing for deposition temperatures between 330 and 520 degrees C. Deposition ... [Appl. Phys. Lett. 100, 202107 (2012)] published Wed May 16, 2012.

Photothermal cantilever deflection spectroscopy of a photosensitive polymer

Minhyuk Yun, Seonghwan Kim, Dongkyu Lee, Namchul Jung, Inseok Chae et al.
The mechanical and chemical information of a poly(methyl methacrylate) (PMMA) film on a microcantilever were simultaneously acquired by photothermal cantilever deflection spectroscopy as a function of ultraviolet (UV) irradiation time. Nanomechanical infrared (IR) spectra from the PMMA-coated microc ... [Appl. Phys. Lett. 100, 204103 (2012)] published Wed May 16, 2012.

Shot noise suppression in InGaAs/InGaAsP quantum channels

Yoshitaka Nishihara, Shuji Nakamura, Kensuke Kobayashi, Teruo Ono, Makoto Kohda et al.
We have measured the shot noise in a quantum point contact (QPC) fabricated by using InGaAs/InGaAsP heterostructure, whose conductance can be electrically tuned by the gate voltages. The reduced shot noise is observed when the QPC conductance equals to N(2e/h) (N = 4, 5, and 6), which is the direct ... [Appl. Phys. Lett. 100, 203111 (2012)] published Wed May 16, 2012.

Structure of iron nanolayers embedded in amorphous alloys

M. Ghafari, H. Hahn, R. A. Brand, R. Mattheis, Y. Yoda et al.
Metalloid-free magnetic amorphous layers have been searched for their presumably high magnetic density. Multilayers of iron and amorphous boron-doped cobalt-iron have been studied with this in mind. Samples with various Fe thicknesses and a constant thickness of amorphous boron doped cobalt-iron wer ... [Appl. Phys. Lett. 100, 203108 (2012)] published Wed May 16, 2012.

Taming the thermal emissivity of metals: A metamaterial approach

N. Mattiucci, G. D'Aguanno, A. Alu, C. Argyropoulos, J. V. Foreman et al.
We demonstrate the possibility of realizing temporally coherent, wide-angle, thermal radiation sources based on the metamaterial properties of metallic gratings. In contrast to other approaches, we do not rely on the excitation of surface waves such as phonon-polaritons, plasmon-polaritons, or guide ... [Appl. Phys. Lett. 100, 201109 (2012)] published Wed May 16, 2012.

Color control through plasmonic metal gratings

M. A. Vincenti, M. Grande, D. de Ceglia, T. Stomeo, V. Petruzzelli et al.
We experimentally demonstrate the color tuning abilities of two-dimensional periodic arrays of gold nano-patches on silicon substrate. We observe that changes in the geometrical parameters of the array can shift significantly the plasmonic resonance that occurs at the edge of the plasmonic band gap. ... [Appl. Phys. Lett. 100, 201107 (2012)] published Wed May 16, 2012.

The study of perpendicular magnetic anisotropy in CoFeB sandwiched by MgO and tantalum layers using polarized neutron reflectometry

T. Zhu, Y. Yang, R. C. Yu, H. Ambaye, V. Lauter et al.
The perpendicular magnetic anisotropy (PMA) in CoFeB sandwiched by MgO and tantalum layers was investigated using anomalous Hall effect and polarized neutron reflectometry. It was found that a large PMA in the CoFeB above MgO layer was related to its low magnetization compared to the case of CoFeB u ... [Appl. Phys. Lett. 100, 202406 (2012)] published Wed May 16, 2012.

Interfacial interaction of gas molecules and single-walled carbon nanotubes

Jun Zhong, Jauwern Chiou, Chungli Dong, Per-Anders Glans, Way-Faung Pong et al.
The interfacial interaction between single-walled carbon nanotubes (SWNTs) and various gas molecules (H, He, and N) at different pressures has been probed by in situ x-ray absorption near-edge structure (XANES) spectroscopy. Experimental results reveal the different strength of interfacial interacti ... [Appl. Phys. Lett. 100, 201605 (2012)] published Wed May 16, 2012.

Observation of a Coulomb blockade in strontium titanate thin films

V. Grosse, F. Schmidl, and P. Seidel
We report on the study of the low temperature electronic transport in strontium titanate thin films having a thickness of 2530 nm. I-V characteristics measured below 4.2 K show unique structures which are evidence for the occurrence of a Coulomb blockade. Simulations of the measured characteristics ... [Appl. Phys. Lett. 100, 203110 (2012)] published Wed May 16, 2012.

Theoretical study of Si-based ionic switch

Takashi Yamauchi, Moon Young Yang, Katsumasa Kamiya, Kenji Shiraishi, and Takashi Nakayama
We studied the formation/dissolution of a silver (Ag) filament in a silicon (Si) layer through the first-principles calculations. We found these processes take place reversibly by switching the polarity of the bias voltage, bringing about the large resistance change of the Si layer. Furthermore, we ... [Appl. Phys. Lett. 100, 203506 (2012)] published Tue May 15, 2012.

Charge instability of atomic-layer deposited TaSiO insulators on Si, InP, and InGaAs

V. V. Afanas'ev, H.-Y. Chou, N. H. Thoan, C. Adelmann, H. C. Lin et al.
Low barriers for electrons are found to be the reason for significant charge instability at interfaces of (100)InP and (100)InGaAs with atomic-layer deposited TaSiO insulators. The formation of these reduced barriers is associated with the growth of a narrow-bandgap interlayer between the semiconduc ... [Appl. Phys. Lett. 100, 202104 (2012)] published Tue May 15, 2012.

Dynamics of localized excitons in GaInNAs/GaAs quantum well: Experimental studies and Monte-Carlo simulations

M. Baranowski, R. Kudrawiec, M. Latkowska, M. Syperek, J. Misiewicz et al.
Time resolved photoluminescence (PL) spectroscopy has been applied to study dynamics of localized excitons in a single GaInNAs/GaAs quantum well (QW). The decay time constant, tau, has been determined for different PL peak energies at various temperatures. An increase in temperature produced two eff ... [Appl. Phys. Lett. 100, 202105 (2012)] published Tue May 15, 2012.

Metal-like conductivity exhibited by triboelectrically deposited polyaniline (emeraldine base) particles on microtextured SiC surfaces

I. S. Bayer, V. Caramia, A. Biswas, R. Cingolani, and A. Athanassiou
We demonstrate a simple and rapid way to deposit layers of polyaniline (emeraldine base) particles on flexible microtextured silicon carbide surfaces by contact charging them using a smooth dielectric rubber. Wetting of the layers by trifluoroacetic acid creates conductive, continuous polymeric film ... [Appl. Phys. Lett. 100, 201604 (2012)] published Tue May 15, 2012.

Response to Comment on `Observation of anomalous acoustic phonon dispersion in SrTiO by broadband stimulated Brillouin scattering'[Appl. Phys. Lett. 100, 206101 (2012)]

S. Brivio, D. Polli, A. Crespi, R. Osellame, G. Cerullo et al.
Abstract not available. [Appl. Phys. Lett. 100, 206102 (2012)] published Tue May 15, 2012.

Stoichiometry of SrTiO films grown by pulsed laser deposition

G. Z. Liu, Q. Y. Lei, and X. X. Xi
We have investigated the effects of laser energy density and oxygen pressure on the cation stoichiometry of homoepitaxial (001) SrTiO thin film grown by pulsed laser deposition. A broad growth window was found for near stoichiometric, uniform SrTiO thin films. At oxygen pressures, at or below 10Torr ... [Appl. Phys. Lett. 100, 202902 (2012)] published Tue May 15, 2012.

Mapping return currents in laser-generated Z-pinch plasmas using proton deflectometry

M. J.-E. Manuel, N. Sinenian, F. H. Seguin, C. K. Li, J. A. Frenje et al.
Dynamic return currents and electromagnetic field structure in laser-generated Z-pinch plasmas have been measured using proton deflectometry. Experiments were modeled to accurately interpret deflections observed in proton radiographs. Current flow is shown to begin on axis and migrate outwards with ... [Appl. Phys. Lett. 100, 203505 (2012)] published Tue May 15, 2012.

Anomalies of magnetic properties and magnetovolume effect in CdMnGeAs at hydrostatic pressure

A. Yu. Mollaev, I. K. Kamilov, R. K. Arslanov, T. R. Arslanov, U. Z. Zalibekov et al.
We present the experimental results of the effect hydrostatic pressure up to P <= 7 GPa applied at the room temperatures in diluted magnetic semiconductor CdMnGeAs (x = 0.06 0.3). We have found the pressure areas at which anomalies in magnetic properties were observed. Induced by hydrostatic pressu ... [Appl. Phys. Lett. 100, 202403 (2012)] published Tue May 15, 2012.

Transport properties of graphene nanoribbon transistors on chemical-vapor-deposition grown wafer-scale graphene

Wan Sik Hwang, Kristof Tahy, Xuesong Li, Huili (Grace) Xing, Alan C. Seabaugh et al.
Graphene nanoribbon (GNR) field-effect transistors (FETs) with widths down to 12 nm have been fabricated by electron beam lithography using a wafer-scale chemical vapor deposition (CVD) process to form the graphene. The GNR FETs show drain-current modulation of approximately 10 at 300 K, increasing ... [Appl. Phys. Lett. 100, 203107 (2012)] published Tue May 15, 2012.

Red-green-blue polymer light-emitting diode pixels printed by optimized laser-induced forward transfer

James Shaw Stewart, Thomas Lippert, Matthias Nagel, Frank Nuesch, and Alexander Wokaun
An optimized laser-induced forward transfer (LIFT) technique has been used to fabricate tri-color organic light-emitting diode (OLED) pixels. At reduced pressures, and with a defined donor-receiver gap, patterned depositions of polyfluorene-based OLED pixels have been achieved. OLED pixel functional ... [Appl. Phys. Lett. 100, 203303 (2012)] published Tue May 15, 2012.

Effect of oxygen deficiency on room temperature ferromagnetism in Co doped ZnO

Hao Gu, Wen Zhang, Yongbing Xu, and Mi Yan
We investigated the correlation between magnetization and oxygen vacancies in ZnCoO nanoparticles. Enhanced magnetizations were found in SiO nanopowders and carbon nanotubes (CNTS) treated ZnCoO, which are attributed to minimizing nanoparticle size and increasing oxygen vacancy concentration. After ... [Appl. Phys. Lett. 100, 202401 (2012)] published Tue May 15, 2012.

Control of tensile strain in germanium waveguides through silicon nitride layers

A. Ghrib, M. de Kersauson, M. El Kurdi, R. Jakomin, G. Beaudoin et al.
Germanium ridge waveguides can be tensilely strained using silicon nitride thin films as stressors. We show that the strain transfer in germanium depends on the width of the waveguides. Carrier population in the zone center Gamma valley can also be significantly increased when the ridges are oriente ... [Appl. Phys. Lett. 100, 201104 (2012)] published Tue May 15, 2012.

Plasmons in electrostatically doped graphene

Sukosin Thongrattanasiri, Ivan Silveiro, and F. Javier Garcia de Abajo
Graphene has raised high expectations as a low-loss plasmonic material in which the plasmon properties can be controlled via electrostatic doping. Here, we analyze realistic configurations, which produce inhomogeneous doping, in contrast to what has been so far assumed in the study of plasmons in na ... [Appl. Phys. Lett. 100, 201105 (2012)] published Tue May 15, 2012.

Two-photon fluorescence properties of curcumin as a biocompatible marker for confocal imaging

Abhishek Kumar, Lian Li, Akanksha Chaturvedi, Joseph Brzostowski, Joshna Chittigori et al.
Two-photon (TP) fluorescence properties of an antioxidant and anti-tumor molecule, curcumin, were investigated. The two-photon absorption (TPA) action cross-section was measured in organic solvents and found to be 6 GM in tetrahydrofuran and 2 GM in dimethyl sulfoxide. The measured TPA cross-section ... [Appl. Phys. Lett. 100, 203701 (2012)] published Tue May 15, 2012.

Combined microscopies study of the C-contamination induced by extreme-ultraviolet radiation: A surface-dependent secondary-electron-based model

S. Prezioso, M. Donarelli, F. Bisti, L. Palladino, S. Santucci et al.
SiO and AlO surfaces exposed to periodically modulated extreme ultraviolet (EUV) light (lambda = 46.9 nm) have been investigated at the [mu]m scale by optical microscopy, scanning electron microscopy, scanning Auger microscopy, atomic force microscopy, and Kelvin probe force microscopy. The formatio ... [Appl. Phys. Lett. 100, 201603 (2012)] published Tue May 15, 2012.

Dynamical band-engineering of spin-polarized edge-states in normal insulators

B. H. Wu, Qin Liu, Xunya Jiang, and J. C. Cao
We investigate the electronic and transport properties of a normal insulator in form of a zigzag ribbon based on the Kane-Mele model subjected to circularly polarized radiation. Our results show that chiral edge-states can be induced in the band gap of the quasi-energy spectra under periodic driving ... [Appl. Phys. Lett. 100, 203106 (2012)] published Tue May 15, 2012.

Effect of cold working in a magnetic field on the shape of a ferromagnetic nanocontact

Marc Muller, Richard Montbrun, Christoph Surgers, and Hilbert v. Lohneysen
The role of a magnetic field present during formation of a ferromagnetic nanocontactestablished by mechanically pulling a thin dysprosium wireis investigated. We demonstrate that the shape of the nanocontact depends on the strength and direction of the magnetic field applied during plastic deformati ... [Appl. Phys. Lett. 100, 202402 (2012)] published Tue May 15, 2012.

Mesoscopic resistor as a self-calibrating quantum noise source

N. Bergeal, F. Schackert, L. Frunzio, D. E. Prober, and M. H. Devoret
We present a method for the measurement of the noise of microwave amplifiers operating at the single photon level. It is based on the shot noise produced by a nanowire resistor in the hot electron regime. This noise source is simply controlled by a dc current and offers the advantage of being self-c ... [Appl. Phys. Lett. 100, 203507 (2012)] published Tue May 15, 2012.

Enhancement in coupling efficiency from laser to forward hot electrons by conical nanolayered targets

Jinqing Yu (余金清), Weimin Zhou (周维民), Lihua Cao (曹莉华), Zongqing Zhao (赵宗清), Leifeng Cao (曹磊峰) et al.
To improve the energy coupling efficiency from laser to forward hot electrons, we propose a conical nanolayered target (CNT) and investigate by two-dimensional particle-in-cell simulations. Compared with nanolayered target, the energy coupling efficiency is enhanced from 34% to more than 68%. Detail ... [Appl. Phys. Lett. 100, 204101 (2012)] published Tue May 15, 2012.

Relief of surface stress at steps during displacive adsorption of As on Si(111)

C. X. Zheng, W. X. Tang, and D. E. Jesson
The displacive adsorption of As on 1 x 1 Si(111) is examined using surface electron microscopy. High temperature adsorption experiments are used to reduce the As chemical potential and identify regions of enhanced As incorporation in the vicinity of steps. This is explained by a reduction in tensi ... [Appl. Phys. Lett. 100, 201602 (2012)] published Tue May 15, 2012.

Silicon germanium tin alloys formed by pulsed laser induced epitaxy

S. Stefanov, J. C. Conde, A. Benedetti, C. Serra, J. Werner et al.
Pulsed lased induced epitaxy is used to obtain heteroepitaxial GeSn and SiGeSn alloys with graded composition on Si(001) substrates. The transition from GeSn to SiGeSn was achieved by varying the number of laser pulses accordingly with the level of intermixing between Si, Ge, and Sn. Melt duration, ... [Appl. Phys. Lett. 100, 204102 (2012)] published Tue May 15, 2012.

Modeling charge transfer at organic donor-acceptor semiconductor interfaces

Deniz Cakir, Menno Bokdam, Michel P. de Jong, Mats Fahlman, and Geert Brocks
We develop an integer charge transfer model for the potential steps observed at interfaces between donor and acceptor molecular semiconductors. The potential step can be expressed as the difference between the Fermi energy pinning levels of electrons on the acceptor material and holes on the donor m ... [Appl. Phys. Lett. 100, 203302 (2012)] published Tue May 15, 2012.

Comment on Observation of anomalous acoustic phonon dispersion in SrTiO by broadband stimulated Brillouin scattering [Appl. Phys. Lett. 98, 211907 (2011)]

A. Devos, Y.-C. Wen, P.-A. Mante, and C.-K. Sun
Abstract not available. [Appl. Phys. Lett. 100, 206101 (2012)] published Tue May 15, 2012.

Generalized approach to the description of recombination kinetics in bulk heterojunction solar cellsextending from fully organic to hybrid solar cells

Bert Conings, Linny Baeten, Hans-Gerd Boyen, Donato Spoltore, Jan D'Haen et al.
Lately, research efforts in photovoltaics towards hybrid solar cells based on nanostructured metal oxides and conjugated polymers have been intensifying. However, very limited effort has been spent so far to investigate their recombination kinetics in comparison with their fully organic counterpart. ... [Appl. Phys. Lett. 100, 203905 (2012)] published Tue May 15, 2012.

Shear-mode magnetostrictive/piezoelectric composite with an enhanced magnetoelectric coefficient

Yaojin Wang, D. Hasanyan, Jiefang Li, D. Viehland, and Haosu Luo
A magnetoelectric (ME) laminate heterostructure consisting of two shear-mode piezoelectric Pb(MgNb)O-30PbTiO (PMN-PT) single crystal layers, a longitudinally magnetized magnetostrictive TbDyFe alloy plate, and a mechanical clamping brass substrate has been demonstrated that has a notably superior ME ... [Appl. Phys. Lett. 100, 202903 (2012)] published Tue May 15, 2012.

Reversibility in the inverse magnetocaloric effect in MnGaC studied by direct adiabatic temperature-change measurements

O. Cakiotar and M. Acet
Thermal-hysteresis affects adversely the reversibility of the magnetocaloric effect around a first order magnetostructural transition. In MnGaC, a first order antiferromagnetic-ferromagnetic transition is accompanied by a volume-change and a 5 K thermal-hysteresis. We study the reversibility of the ... [Appl. Phys. Lett. 100, 202404 (2012)] published Tue May 15, 2012.

Magnitude-tunable sub-THz shear phonons in a non-polar GaN multiple-quantum-well p-i-n diode

Chien-Cheng Chen, Huei-Min Huang, Tien-Chang Lu, Hao-Chung Kuo, and Chi-Kuang Sun
Coherent transverse acoustic phonons are optically generated and detected through the piezoelectric coupling between the build-in electric fields and shear strains of a non-polar GaN multiple quantum wells embedded in a p-n junction. By optical transient transmission change measurement, the phonon f ... [Appl. Phys. Lett. 100, 201905 (2012)] published Tue May 15, 2012.

Nonlinear size-dependent melting of the silica-encapsulated silver nanoparticles

Chengying Tang (唐成颖), Yun-Mo Sung, and Joonho Lee
In spite of the recent report of the in situ high-resolution transmission electron microscopy observation of the melting of Ag nanoparticles (NPs) in Chen et al. [Appl. Phys. Lett. 96, 253104 (2010)], no consistent experimental investigation coupled with theoretical analysis has been reported so far ... [Appl. Phys. Lett. 100, 201903 (2012)] published Mon May 14, 2012.

Ring-shaped NdFeB-based magnetic tweezers enables oscillatory microrheology measurements

Jun Lin and Megan T. Valentine
We present the design and characterization of a magnetic tweezers device that employs a ring-shaped neodymium iron boron (NdFeB) magnet. Because the gradient of the magnetic field generated by ring magnets changes sign along its symmetry axis, magnetic tweezers devices that employ ring magnets can b ... [Appl. Phys. Lett. 100, 201902 (2012)] published Mon May 14, 2012.

Controlling flux flow dissipation by changing flux pinning in superconducting films

G. Grimaldi, A. Leo, A. Nigro, A. V. Silhanek, N. Verellen et al.
We study the flux flow state in superconducting materials characterized by rather strong intrinsic pinning, such as Nb, NbN, and nanostructured Al thin films, in which we drag the superconducting dissipative state into the normal state by current biasing. We modify the vortex pinning strength either ... [Appl. Phys. Lett. 100, 202601 (2012)] published Mon May 14, 2012.

Direct evidence of n-type doping in organic light-emitting devices: N free Cs doping from CsN

Jeihyun Lee, Hyunbok Lee, Pyungeun Jeon, Kwangho Jeong, Tae Gun Kim et al.
Cesium azide (CsN) is confirmed to be decomposed during thermal evaporation. Only Cs could be deposited on tris(8-hydroxyquinolinato)aluminum (Alq) and n-type doping is easily achieved. Organic light-emitting devices with CsN show highly improved current density-luminance-voltage characteristics com ... [Appl. Phys. Lett. 100, 203301 (2012)] published Mon May 14, 2012.

Optical and acoustic phonon modes in strained InGaAs/GaAs rolled up tubes

T. Angelova, N. Shtinkov, Ts. Ivanov, V. Donchev, A. Cantarero et al.
Rolled-up semiconductor tubes of various diameters made of alternating InGaAs/GaAs layers have been investigated by means of Raman scattering. The optical and acoustic phonon modes of individual tubes have been studied and compared with the characteristics of the surrounding material. After tube for ... [Appl. Phys. Lett. 100, 201904 (2012)] published Mon May 14, 2012.

Parametric energy conversion of thermoacoustic vibrations

C. Guthy, C. W. Van Neste, S. Mitra, S. Bhattacharjee, and T. Thundat
We demonstrate a parametric energy conversion method of thermoacoustic (TA) vibrations into electrical oscillations of a LC circuit. The inductance modulation necessary to excite the parametric oscillations is achieved by varying the air gap between two halves of a ferrite E-core coil. As a proof-of ... [Appl. Phys. Lett. 100, 203902 (2012)] published Mon May 14, 2012.

Sodium ionic conduction in complex hydrides with [BH] and [NH] anions

Motoaki Matsuo, Shingo Kuromoto, Toyoto Sato, Hiroyuki Oguchi, Hitoshi Takamura et al.
We report the experimental results of structural and sodium ionic conductive properties of the Na(BH)Na(NH)NaI system. Na(BH)(NH) with [BH] and [NH] complex anions formed by combining Na(BH) and Na(NH) complex hydrides shows the most superior sodium ionic conductivity of 2 x 10 S/cm at 300 K becau ... [Appl. Phys. Lett. 100, 203904 (2012)] published Mon May 14, 2012.

Manipulation of a single electron spin in a quantum dot without magnetic field

S. Bednarek, J. Pawlowski, and A. Skubis
In this paper, we propose the construction of a nanodevice performing the spin rotations of an electron confined in an electrostatic quantum dot without the use of a magnetic field. Sinusoidally varying voltage applied in different phases to four gates causes the electron to move along a two-dimensi ... [Appl. Phys. Lett. 100, 203103 (2012)] published Mon May 14, 2012.

Near threshold all-optical backaction amplifier

Terry G. McRae and Warwick P. Bowen
A near threshold all-optical backaction amplifier is realized. Operating near threshold in an integrated micron scale architecture allows a nearly three orders of magnitude improvement in both gain and optical power requirements over the only previous all-optical implementation, with 37 dB of gain a ... [Appl. Phys. Lett. 100, 201101 (2012)] published Mon May 14, 2012.

High-power, stable Ka/V dual-band gyrotron traveling-wave tube amplifier

Chien-Lun Hung
A dual-band amplifier can reduce the size, cost, and weight of a transmitter in dual-band radar and communication systems. This study proposes and theoretically investigates a gyrotron traveling-wave tube (gyro-TWT) amplifier capable of dual-band operation. Possible oscillations in the coaxial inter ... [Appl. Phys. Lett. 100, 203502 (2012)] published Mon May 14, 2012.

Silicon-based reproducible and active surface-enhanced Raman scattering substrates for sensitive, specific, and multiplex DNA detection

Z. Y. Jiang, X. X. Jiang, S. Su, X. P. Wei, S. T. Lee et al.
Silicon-based active and reproducible surface-enhanced Raman scattering (SERS) substrate, i.e., silver nanoparticles decorated-silicon wafers (AgNPs@Si), is employed for constructing high-performance sensors. Significantly, the AgNPs@Si, facilely prepared via in situ AgNPs growth on silicon wafers, ... [Appl. Phys. Lett. 100, 203104 (2012)] published Mon May 14, 2012.

Terahertz current oscillations in a gated two-dimensional electron gas with antenna integrated at the channel ends

Alessandra Di Gaspare, Roberto Casini, Vittorio Foglietti, Valeria Giliberti, Ennio Giovine et al.
We studied terahertz current oscillations induced by a frequency-tunable radiation source in a AlGaAs/InGaAs/AlGaAs heterostructure field effect transistor channel. A planar antenna was integrated on-chip, and a substrate lens was used for broadband coupling of free-space radiation at 0.180.72 THz t ... [Appl. Phys. Lett. 100, 203504 (2012)] published Mon May 14, 2012.

Interface trap generation and recovery mechanisms during and after positive bias stress in metal-oxide-semiconductor structures

Piyas Samanta, Heng-Sheng Huang, Shuang-Yuan Chen, Tsung-Jian Tzeng, and Mu-Chun Wang
Interface trap (N) generation and their partial recovery during and after cessation of the positive bias-temperature stress (PBTS) in n-type metal-oxide-semiconductor capacitors have been investigated. The analysis of experimental results indicates that N creation is caused by the depassivation of S ... [Appl. Phys. Lett. 100, 203503 (2012)] published Mon May 14, 2012.

Electronic effects of Se and Pb dopants in TlBr

Holland M. Smith, III, David J. Phillips, Ian D. Sharp, Jeffrey W. Beeman, Daryl C. Chrzan et al.
Deep levels in Se- and Pb-doped bulk TlBr detectors were characterized with photo-induced conductivity transient spectroscopy (PICTS) and cathodoluminescence (CL). Se-doped TlBr revealed two traps with energies of 0.35 and 0.45 eV in PICTS spectra. The Pb-doped material revealed three levels with en ... [Appl. Phys. Lett. 100, 202102 (2012)] published Mon May 14, 2012.

A pathway between Bernal and rhombohedral stacked graphene layers with scanning tunneling microscopy

P. Xu, Yurong Yang, D. Qi, S. D. Barber, M. L. Ackerman et al.
Horizontal shifts in the top layer of highly oriented pyrolytic graphite, induced by a scanning tunneling microscope (STM) tip, are presented. Excellent agreement is found between STM images and those simulated using density functional theory. First-principle calculations identify that the low-energ ... [Appl. Phys. Lett. 100, 201601 (2012)] published Mon May 14, 2012.

Reevaluation of the beneficial effect of Cu(In,Ga)Se grain boundaries using Kelvin probe force microscopy

Zhenhao Zhang, Xiaochen Tang, Oliver Kiowski, Michael Hetterich, Uli Lemmer et al.
Potential variations at grain boundaries are analyzed on the surface and on untreated cross sections of the absorber in a Cu(In,Ga)Se solar cell applying Kelvin probe force microscopy. We observe three different types of potential variations between grain boundaries (dip-, step-, or peak-shape). The ... [Appl. Phys. Lett. 100, 203903 (2012)] published Mon May 14, 2012.

Thermo-optic switch based on transmission-dip shifting in a double-slot photonic crystal waveguide

Kaiyu Cui, Qiang Zhao, Xue Feng, Yidong Huang, Yongzhuo Li et al.
Optical switch based on an ultra-compact double-slot photonic crystal waveguide (DS-PCWG) with a titanium/aluminum microheater is demonstrated. The operating principle relies on shifting a transmission-dip caused by the defect mode coupling in photonic band gap (PBG). Based on the unique mode coupli ... [Appl. Phys. Lett. 100, 201102 (2012)] published Mon May 14, 2012.

Trace analysis of non-basal plane misfit stress relaxation in (20[overline 2]1) and (30[overline 3][overline 1]) semipolar InGaN/GaN heterostructures

Matthew T. Hardy, Po Shan Hsu, Feng Wu, Ingrid L. Koslow, Erin C. Young et al.
We have studied primary and secondary slip systems in the relaxation of lattice mismatch stresses in (20[overline 2]1) and (30[overline 3][overline 1]) semipolar InGaN/GaN heterostructures by analyzing the geometry of traces associated with dislocations employing cathodoluminescence, x-ray diffracti ... [Appl. Phys. Lett. 100, 202103 (2012)] published Mon May 14, 2012.

On the characteristic length scales associated with plastic deformation in metallic glasses

P. Murali, Y. W. Zhang, and H. J. Gao
Atomistic simulations revealed that the spatial correlations of plastic displacements in three metallic glasses, FeP, MgAl, and CuZr, follow an exponential law with a characteristic length scale [script-l] that governs Poisson's ratio nu, shear band thickness t, and fracture mode in these materials. ... [Appl. Phys. Lett. 100, 201901 (2012)] published Mon May 14, 2012.

Analysis of vacancy-induced amorphization of single-layer graphene

Corinne Carpenter, Ashwin Ramasubramaniam, and Dimitrios Maroudas
We report results of a systematic molecular-dynamics study on the vacancy-induced amorphization of single-layer graphene. An inserted vacancy concentration between 5% and 10% marks the onset of the amorphization transition. The computed amorphized configurations are in agreement with recent experime ... [Appl. Phys. Lett. 100, 203105 (2012)] published Mon May 14, 2012.

Partially filled intermediate band of Cr-doped GaN films

S. Sonoda
We investigated the band structure of sputtered Cr-doped GaN (GaCrN) films using optical absorption, photoelectron yield spectroscopy, and charge transport measurements. It was found that an additional energy band is formed in the intrinsic band gap of GaN upon Cr doping, and that charge carriers in ... [Appl. Phys. Lett. 100, 202101 (2012)] published Mon May 14, 2012.

Migration mechanism for atomic hydrogen in porous carbon materials

Badri Narayanan, Yufeng Zhao, and Cristian V. Ciobanu
To explain the fast kinetics of H in porous carbon, we propose that the migration relies on H hopping from a carbon nanotube (CNT) to another. Using density functional theory, we have found that the barrier for H hopping becomes smaller than that for diffusion along a tube for certain CNT separation ... [Appl. Phys. Lett. 100, 203901 (2012)] published Mon May 14, 2012.

Controlled faceting in germanium nanowire growth by switching between vapor-liquid-solid and vapor-solid-solid growth

Miroslav Kolibal, Radek Kalousek, Tomas Vystavel, Libor Novak, and Tomas Sikola
We show that the hexagonal cross-section of germanium nanowires grown in the direction by physical vapor deposition is a consequence of minimization of surface energy of the collector droplet. If the droplet is lost or solidified, two {001} sidewall facets are quickly overgrown and the nanowire exh ... [Appl. Phys. Lett. 100, 203102 (2012)] published Mon May 14, 2012.

Domain tuning in mixed-phase BiFeO thin films using vicinal substrates

Lu You, Shintaro Yasui, Yoshitaka Ehara, Xi Zou, Hui Ding et al.
The structural and ferroelectric domain variants of highly strained BiFeO films grown on vicinal LaSrAlO substrates were studied by piezoelectric force microscopy and high-resolution x-ray reciprocal space mapping. Through symmetry breaking of the substrate surface, ferroelastic domain variants in t ... [Appl. Phys. Lett. 100, 202901 (2012)] published Mon May 14, 2012.

Effect of oxygen-related surface adsorption on the efficiency and stability of ZnO nanorod array ultraviolet light-emitting diodes

W. Z. Liu, H. Y. Xu, J. G. Ma, C. Y. Liu, Y. X. Liu et al.
Ultraviolet light-emitting diodes using MgZnO-coated and bare ZnO nanorod arrays as active layers were manufactured. Both types were exposed to ambient air over a 1-yr period to assess their stability. By monitoring the electroluminescence evolution with air-exposure time and comparing the changes o ... [Appl. Phys. Lett. 100, 203101 (2012)] published Mon May 14, 2012.

Silicon fab-compatible contacts to n-InP and p-InGaAs for photonic applications

S. Jain, M. Sysak, M. Swaidan, and J. Bowers
We report on silicon fab-compatible non-gold ohmic contacts to n-InP and p-InGaAs using Ti/W and Pd/Ge/W based metallization schemes where gold is replaced by aluminum as a thick probe layer. Specific contact resistivity of <1 x 10 [ohm sign] cm and < 2 x 10 [ohm sign] cm is obtained on n-InP an ... [Appl. Phys. Lett. 100, 201103 (2012)] published Mon May 14, 2012.

Columnar thermoelectric elements of linked spheres for miniature electric generation modules

Kenta Takagi, Kimihiro Ozaki, Yasuhiro Kawaguchi, and Hideki Yumi
Thermoelectric elements that were formed from vertically aligned microspheres were fabricated from 500-[mu]m monosized spherical particles of FeVAl alloys with a particle assembly that used pulsed current micro-welding. P-n pairs of the elements consisting of three particles generated relatively lar ... [Appl. Phys. Lett. 100, 203501 (2012)] published Mon May 14, 2012.

Low-temperature dielectric response of NaTaO ceramics and films

A. Tkach, A. Almeida, J. Agostinho Moreira, J. Perez de la Cruz, Y. Romaguera-Barcelay et al.
In this work, NaTaO ceramics are prepared by conventional mixed oxide method and NaTaO films are deposited by RF magnetron sputtering on Si/SiO/TiO/Pt substrates. The dielectric response of the obtained NaTaO ceramics and films is analyzed as a function of frequency and temperature. Between 1 kHz an ... [Appl. Phys. Lett. 100, 192909 (2012)] published Fri May 11, 2012.

Electrical contact resistance in filaments

Xiang-Fa Wu, Zhengping Zhou, and Wang-Min Zhou
Electrical contact resistance (ECR) influences the electrochemical performance of porous electrodes made of stacked discrete materials (e.g., carbon nanotubes, nanofibers, etc.) for use in supercapacitors and rechargeable batteries. This study establishes a simple elasticity-conductivity model for t ... [Appl. Phys. Lett. 100, 193115 (2012)] published Fri May 11, 2012.

Low-kappa organic layer as a top gate dielectric for graphene field effect transistors

G. Mordi, S. Jandhyala, C. Floresca, S. McDonnell, M. J. Kim et al.
We demonstrate the characteristics of dual gated graphene field effect transistors using a thin layer (~7 nm) of parylene-C as a top-gate dielectric. Our devices exhibit good dielectric properties with minimal doping, low leakage current (~10 A/cm at 2 V), and a dielectric constant of ~2.1. Addition ... [Appl. Phys. Lett. 100, 193117 (2012)] published Fri May 11, 2012.

Highly efficient thermal glue for carbon nanotubes based on azide polymers

Yuxiang Ni, Hung Le Khanh, Yann Chalopin, Jinbo Bai, Pierre Lebarny et al.
Equilibrium molecular dynamics (EMD) simulations and experimental data show that the thermal contact resistance (TCR) between carbon nanotube (CNT) and azide-functionalized polymer with C-N bond is significantly decreased compared to that with Van der Waals force interaction. EMD simulations indicat ... [Appl. Phys. Lett. 100, 193118 (2012)] published Fri May 11, 2012.

Impulse breakdown delay in liquid dielectrics

Jouya Jadidian, Markus Zahn, Nils Lavesson, Ola Widlund, and Karl Borg
Theoretical images of streamers, revealing the mechanisms behind impulse breakdown in liquid dielectrics, are presented. Streamers lead to electrical breakdown by forming paths, capable of carrying large current amplitudes between electrodes. Breakdown delays and terminal currents are calculated for ... [Appl. Phys. Lett. 100, 192910 (2012)] published Fri May 11, 2012.

Strained InGaAs metal-oxide-semiconductor field-effect transistors with epitaxial based biaxial strain

SangHyeon Kim, Masafumi Yokoyama, Noriyuki Taoka, Ryosho Nakane, Tetsuji Yasuda et al.
We have demonstrated epitaxial-based biaxially strained InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). Tensile strained InGaAs MOSFETs shows a high peak mobility of 2150 cm/Vs with the enhancement factor of 3.7 against Si MOSFETs. Furthermore, we have investigated the mobility ... [Appl. Phys. Lett. 100, 193510 (2012)] published Fri May 11, 2012.

Room temperature nonlinear operation of a graphene-based three-branch nanojunction device with chemical doping

Shaharin Fadzli Abd Rahman, Seiya Kasai, and Abdul Manaf Hashim
A chemically doped graphene-based three-branch nanojunction device is fabricated on a SiO/p-Si substrate, and its nonlinear operation is characterized at room temperature (RT). By polyethyleneimine doping, the fabricated device shows improved field effect mobility of 14 800 and 16 100 cm/Vs for elec ... [Appl. Phys. Lett. 100, 193116 (2012)] published Fri May 11, 2012.

Detecting giant electrocaloric effect in SrBaNbO single crystals

Mahmoud Aly Hamad
PbZrTiO thin film is the best electrocaloric effect material which has cooling DeltaT per unit field (MV m) about 0.254 under electric field shift DeltaE = 30 kV cm at Curie temperature T = 222 degrees C [A. S. Mischenko, Q. Zhang, J. F. Scott, R. W. Whatmore, N. D. Mathur, Science 311, 1270 (2006) ... [Appl. Phys. Lett. 100, 192908 (2012)] published Fri May 11, 2012.

A model determining optimal doping concentration and material's band gap of tunnel field-effect transistors

William G. Vandenberghe, Anne S. Verhulst, Kuo-Hsing Kao, Kristin De Meyer, Bart Soree et al.
We develop a model for the tunnel field-effect transistor (TFET) based on the Wentzel-Kramer-Brillouin approximation which improves over existing semi-classical models employing generation rates. We hereby introduce the concept of a characteristic tunneling length in direct semiconductors. Based on ... [Appl. Phys. Lett. 100, 193509 (2012)] published Fri May 11, 2012.

Sub-0.1 nm-resolution quantitative scanning transmission electron microscopy without adjustable parameters

C. Dwyer, C. Maunders, C. L. Zheng, M. Weyland, P. C. Tiemeijer et al.
Atomic-resolution imaging in the scanning transmission electron microscope (STEM) constitutes a powerful tool for nanostructure characterization. Here, we demonstrate the quantitative interpretation of atomic-resolution high-angle annular dark-field (ADF) STEM images using an approach that does not ... [Appl. Phys. Lett. 100, 191915 (2012)] published Fri May 11, 2012.

Improved emission efficiency of a-plane GaN light emitting diodes with silica nano-spheres integrated into a-plane GaN buffer layer

S. H. Park, J. Park, D.-J. You, K. Joo, D. Moon et al.
A simple and inexpensive technique to improve the emission efficiency of nonpolar a-plane light emitting diodes (LEDs) is proposed. The 3-dimensional growth nature of a-plane GaN was utilized to form the regrowth template of a-plane GaN. Subsequently, the controlled integration of silica nano-sphere ... [Appl. Phys. Lett. 100, 191116 (2012)] published Fri May 11, 2012.

High-efficiency InAs/GaAs quantum dot solar cells by metalorganic chemical vapor deposition

Katsuaki Tanabe, Denis Guimard, Damien Bordel, and Yasuhiko Arakawa
We fabricate a high-efficiency InAs/GaAs quantum dot (QD) solar cell. It contains five layers of high-density self-assembled InAs QDs grown by metalorganic chemical vapor deposition suppressing open-circuit-voltage (V) degradation. We develop a dual-layer anti-reflection coating of optimum thickness ... [Appl. Phys. Lett. 100, 193905 (2012)] published Thu May 10, 2012.

Encapsulating light-emitting electrochemical cells for improved performance

Amir Asadpoordarvish, Andreas Sandstrom, Shi Tang, Jimmy Granstrom, and Ludvig Edman
We present a functional and scalable encapsulation of light-emitting electrochemical cells (LECs), which results in a measured ambient operation of >400 h at a brightness of >300 cd/m with a maximum efficacy of 6 lm/W, and a linearly extrapolated ambient operation of ~5600 h at >100 cd/m. Our findin ... [Appl. Phys. Lett. 100, 193508 (2012)] published Thu May 10, 2012.

Lattice thermal conductivity diminution and high thermoelectric power factor retention in nanoporous macroassemblies of sulfur-doped bismuth telluride nanocrystals

Yanliang Zhang, Rutvik J. Mehta, Matthew Belley, Liang Han, Ganpati Ramanath et al.
We report ultralow lattice thermal conductivity in the 0.3 <= kappa <= 0.6 W m K range in nanoporous bulk bismuth telluride pellets obtained by sintering chemically synthesized nanostructures, together with single-crystal-like electron mobilities and Seebeck coefficients at comparable charge carrier ... [Appl. Phys. Lett. 100, 193113 (2012)] published Thu May 10, 2012.

Study of charge distribution and charge loss in dual-layer metal-nanocrystal-embedded high-kappa/SiO gate stack

Z. Z. Lwin, K. L. Pey, Q. Zhang, M. Bosman, Q. Liu et al.
In this work, we present a comprehensive experimental study of charge loss mechanisms in a dual-layer metal nanocrystal (DL-MNC) embedded high-kappa/SiO gate stack. Kelvin force microscopy characterization reveals that the internal-electric-field assisted tunneling could be a dominant charge loss me ... [Appl. Phys. Lett. 100, 193109 (2012)] published Thu May 10, 2012.

Elastic, dielectric, and piezoelectric anomalies and Raman spectroscopy of 0.5Ba(TiZr)O-0.5(BaCa)TiO

Dragan Damjanovic, Alberto Biancoli, Leili Batooli, Amirhossein Vahabzadeh, and Joe Trodahl
The solid solution 0.5Ba(Ti.Zr)O-0.5(BaCa)TiO (BCZT) is a promising lead-free piezoelectric material with exceptionally high piezoelectric coefficients. The strong response is related to structural instabilities close to ambient temperature. We report here on temperature-induced anomalies in the die ... [Appl. Phys. Lett. 100, 192907 (2012)] published Thu May 10, 2012.

Direct assembly of three-dimensional mesh plasmonic rolls

Fu Min Huang, Jatin K. Sinha, Nicholas Gibbons, Philip N. Bartlett, and Jeremy J. Baumberg
A direct-assembly method to construct three-dimensional (3D) plasmonic nanostructures yields porous plasmonic rolls through the strain-induced self-rolling up of two-dimensional metallic nanopore films. This route is scalable to different hole sizes and film thicknesses, and applicable to a variety ... [Appl. Phys. Lett. 100, 193107 (2012)] published Thu May 10, 2012.

Cd-free buffer layer materials on CuZnSn(SSe): Band alignments with ZnO, ZnS, and InS

D. Aaron R. Barkhouse, Richard Haight, Noriyuki Sakai, Homare Hiroi, Hiroki Sugimoto et al.
The heterojunctions formed between CuZnSn(SSe) (CZTSSe) and three Cd-free n-type buffers, ZnS, ZnO, and InS, were studied using femtosecond ultraviolet photoemission and photovoltage spectroscopy. The electronic properties including the Fermi level location at the interface, band bending in the CZTS ... [Appl. Phys. Lett. 100, 193904 (2012)] published Thu May 10, 2012.

Vertical conduction mechanism of the epitaxial graphene/n-type 4H-SiC heterojunction at cryogenic temperatures

M. J. Tadjer, T. J. Anderson, K. D. Hobart, L. O. Nyakiti, V. D. Wheeler et al.
Vertical diodes of epitaxial graphene on n 4H-SiC were investigated. The graphene Raman spectra exhibited a higher intensity in the G-line than the 2D-line, indicative of a few-layer graphene film. Rectifying properties improved at low temperatures as the reverse leakage decreased over six orders of ... [Appl. Phys. Lett. 100, 193506 (2012)] published Thu May 10, 2012.

Entropy-enthalpy compensation may be a useful interpretation tool for complex systems like protein-DNA complexes: An appeal to experimentalists

E. B. Starikov and B. Norden
In various chemical systems, enthalpy-entropy compensation (EEC) is a well-known rule of behavior, although the physical roots of it are still not completely understood. It has been frequently questioned whether EEC is a truly physical phenomenon or a coincidence due to trivial mathematical connecti ... [Appl. Phys. Lett. 100, 193701 (2012)] published Thu May 10, 2012.

Anomalous enhancement of the thermoelectric figure of merit by V co-doping of Nb-SrTiO

K. Ozdogan, M. Upadhyay Kahaly, H. N. Alshareef, and U. Schwingenschlogl
The effect of V co-doping of Nb-SrTiO is studied by full-potential density functional theory. We obtain a stronger increase of the carrier density for V than for Nb dopants. While in Nb-SrTiO a high carrier density counteracts a high thermoelectric figure of merit, the trend is inverted by V co-dopi ... [Appl. Phys. Lett. 100, 193110 (2012)] published Thu May 10, 2012.

Topological asymmetry induced electronic transport in three terminal graphene nanoribbon structure

En-Jia Ye, Wen-Quan Sui, and Xuean Zhao
Topological configurations play an important role in graphene nanoribbon based devices. In this work, the Buttiker's ac transport theory is used to study an asymmetric three terminal graphene nanoribbon structure. With the help of Green's function and related parameters, we show that the topological ... [Appl. Phys. Lett. 100, 193303 (2012)] published Thu May 10, 2012.

Fullerene as electrical hinge

Neng Wan, Pascal Perriat, Li-Tao Sun, Qing-An Huang, Jun Sun et al.
The current study demonstrates that fullerenes with sizes between 1.9 nm and 3.3 nm serve as an efficient electrical hinges for interconnecting sub-5 nm carbon nanotubes (CNTs). Three modes of such soft connections were validated via transmission electron microscopy employing in-situ nano-manipulati ... [Appl. Phys. Lett. 100, 193111 (2012)] published Thu May 10, 2012.

Nm-scale measurements of fast surface potential transients in an AlGaN/GaN high electron mobility transistor

D. W. Cardwell, A. R. Arehart, C. Poblenz, Y. Pei, J. S. Speck et al.
Fast, bias-induced, surface potential transients (SPTs) and conductance transients (CTs) were simultaneously measured on an AlGaN/GaN high electron mobility transistor. SPTs measured near the drain-side gate edge and CTs have nearly the same shape and are well-fit with two exponentials having room-t ... [Appl. Phys. Lett. 100, 193507 (2012)] published Thu May 10, 2012.

Fast switching of a ground state of a reconfigurable array of magnetic nano-dots

Roman Verba, Gennadiy Melkov, Vasil Tiberkevich, and Andrei Slavin
We show numerically that a ground state (ferromagnetic or chessboard antiferromagnetic) and microwave absorption frequency of a dipolarly coupled two-dimensional array of axially magnetized magnetic nano-dots can be switched by application of bias magnetic field pulses (duration 3070 ns). Switching ... [Appl. Phys. Lett. 100, 192412 (2012)] published Thu May 10, 2012.

Investigation of CuSbTe alloy for high-speed phase change random access memory applications

Yegang Lu, Sannian Song, Zhitang Song, Feng Rao, Liangcai Wu et al.
The thermal stability of amorphous SbTe film can be significantly improved by the addition of Cu. CuSbTe alloy is considered to be a potential candidate for phase change random access memory (PCRAM), as evidenced by a higher crystallization temperature, a better data retention ability, and a faster ... [Appl. Phys. Lett. 100, 193114 (2012)] published Thu May 10, 2012.

Engineering direct-indirect band gap transition in wurtzite GaAs nanowires through size and uniaxial strain

Andrew Copple, Nathaniel Ralston, and Xihong Peng
Electronic structures of wurtzite GaAs nanowires in the [0001] direction were studied using first-principles calculations. It was found that the band gap of GaAs nanowires experiences a direct-to-indirect transition when the diameter of the nanowires is smaller than ~28 A. For those thin GaAs nanowi ... [Appl. Phys. Lett. 100, 193108 (2012)] published Thu May 10, 2012.

Real-time observation of Escherichia coli cells under irradiation with a 2-MeV H microbeam

Mikio Kato, Walter Meissl, Kenji Umezawa, Tokihiro Ikeda, and Yasunori Yamazaki
A high-energy H microbeam generated by tapered glass capillary optics was applied to a single Escherichia coli cell, in order to evaluate the effects of irradiation on the activity of the flagellar motor and cell growth in real time. The flagellar motor of the tethered cells was stopped by irradiati ... [Appl. Phys. Lett. 100, 193702 (2012)] published Thu May 10, 2012.

Utility of the inverse partial fluorescence for electronic structure studies of battery materials

H. Wadati, A. J. Achkar, D. G. Hawthorn, T. Z. Regier, M. P. Singh et al.
X-ray absorption spectroscopy is one of the most widely used experimental techniques to study the electronic and spatial structure of materials. Fluorescence yield mode is bulk-sensitive, but has several serious problems coming from saturation effects. In this study, we show the usefulness of partia ... [Appl. Phys. Lett. 100, 193906 (2012)] published Thu May 10, 2012.

Simultaneous visualization of oxygen vacancies and the accompanying cation shifts in a perovskite oxide by combining annular imaging techniques

Shunsuke Kobayashi, Scott D. Findlay, Naoya Shibata, Teruyasu Mizoguchi, Yukio Sato et al.
The defect structures around oxygen vacancies in perovskite-type oxides play very important roles in determining material properties through the change of the electronic state. Therefore, from the viewpoint of developing condensed matter physics and technological applications, it is crucial to obtai ... [Appl. Phys. Lett. 100, 193112 (2012)] published Thu May 10, 2012.

A universal noncontact flowmeter for liquids

Andre Wegfrass, Christian Diethold, Michael Werner, Thomas Frohlich, Bernd Halbedel et al.
Lorentz force velocimetry (LFV) is a noncontact electromagnetic flow measurement technique for liquid metals that is currently used in fundamental research and metallurgy. Up to now, the application of LFV was limited to the narrow class of liquids whose electrical conductivity is of the order 10 S/ ... [Appl. Phys. Lett. 100, 194103 (2012)] published Thu May 10, 2012.

Guided-mode-resonance-coupled plasmonic-active SiO nanotubes for surface enhanced Raman spectroscopy

Xiaobin Xu, Dihan Hasan, Lei Wang, Swapnajit Chakravarty, Ray T. Chen et al.
We demonstrate a surface enhanced Raman scattering (SERS) substrate by integrating plasmonic-active SiO nanotubes into SiN gratings. First, the dielectric grating that is working under guided mode resonance (GMR) provides enhanced electric field for localized surface plasmon polaritons on the surfac ... [Appl. Phys. Lett. 100, 191114 (2012)] published Thu May 10, 2012.

Model for direct-transition gain in a Ge-on-Si laser

Weng W. Chow
This paper describes a laser gain model for the direct, Gamma-point transition in bulk Ge. The model allows calculation of gain and spontaneous-emission spectra for arbitrary strain, as well as doping and injected carrier densities. Many-body effects are included at the level of the screened Hartree ... [Appl. Phys. Lett. 100, 191113 (2012)] published Thu May 10, 2012.

Surface oxide on thin films of yttrium hydride studied by neutron reflectometry

T. Mongstad, C. Platzer-Bjorkman, J. P. Maehlen, B. C. Hauback, S. Zh. Karazhanov et al.
The applicability of standard methods for compositional analysis is limited for H-containing films. Neutron reflectometry is a powerful, non-destructive method that is especially suitable for these systems due to the large negative scattering length of H. In this work, we demonstrate how neutron ref ... [Appl. Phys. Lett. 100, 191604 (2012)] published Thu May 10, 2012.

On the origin of the 265 nm absorption band in AlN bulk crystals

Ramon Collazo, Jinqiao Xie, Benjamin E. Gaddy, Zachary Bryan, Ronny Kirste et al.
Single crystal AlN provides a native substrate for Al-rich AlGaN that is needed for the development of efficient deep ultraviolet light emitting and laser diodes. An absorption band centered around 4.7 eV (~265 nm) with an absorption coefficient above 1000 cm is observed in these substrates. Based o ... [Appl. Phys. Lett. 100, 191914 (2012)] published Thu May 10, 2012.

Terahertz coherent control of surface plasmon polariton propagation in subwavelength metallic hole arrays

Gaofang Li, Zuanming Jin, Xin Xue, Xian Lin, Guohong Ma et al.
We demonstrate the terahertz coherent control of extraordinary transmission through subwavelength metallic hole arrays with double terahertz pulses. The interference of excitations of surface plasmon polaritons (SPPs) by two THz pulses sequence is employed to control the propagation of SPPs in the p ... [Appl. Phys. Lett. 100, 191115 (2012)] published Thu May 10, 2012.

High fraction of substitutional phosphorus in a (100) diamond epilayer with low surface roughness

M.-A. Pinault-Thaury, B. Berini, I. Stenger, E. Chikoidze, A. Lusson et al.
For high power electronics, diamond is a promising semiconductor with phosphorus being the current substitutional donor. However, up to now, in (100) oriented grown diamond, only a small fraction of phosphorus atoms is incorporated in substitutional sites (<30%) and the epilayer surface exhibits mac ... [Appl. Phys. Lett. 100, 192109 (2012)] published Thu May 10, 2012.

Sequential three-step three-photon near-infrared quantum splitting in beta-NaYF:Tm

D. C. Yu, S. Ye, M. Y. Peng, Q. Y. Zhang, and L. Wondraczek
We report on sequential three-step three-photon near-infrared (NIR) quantum splitting in Tm-doped beta-NaYF, where an incident blue photon around 470 nm is split into three NIR photons (1165, 1466, and 1800 nm). The underlying mechanism is analyzed by means of static and dynamic photoemission spectr ... [Appl. Phys. Lett. 100, 191911 (2012)] published Thu May 10, 2012.

Stretch-induced softening of bending rigidity in graphene

Xinghua Shi, Bo Peng, Nicola M. Pugno, and Huajian Gao
First principle calculations are performed to show that the bending rigidity of graphene can be softened considerably with in-plane stretching. This phenomenon can be attributed to stretch-induced loosening of atomic packing and should be of fundamental significance for graphene-based structures and ... [Appl. Phys. Lett. 100, 191913 (2012)] published Thu May 10, 2012.

GaN epitaxy on Cu(110) by metal organic chemical vapor deposition

Qiming Li, Jeffery Figiel, George Wang, Huiwen Xu, and Ganesh Balakrishnan
We demonstrate that Cu can be a suitable substrate material for c-plane GaN epitaxy using metal organic chemical vapor deposition. By using a low temperature AlN buffer layer, Ga and Cu alloying can be prevented so that GaN layer can be grown on Cu at a temperature of 1000 degrees C. An epitaxial r ... [Appl. Phys. Lett. 100, 192110 (2012)] published Thu May 10, 2012.

Nanocrystalline-to-amorphous transition in nanolaminates grown by low temperature atomic layer deposition and related mechanical properties

R. Raghavan, M. Bechelany, M. Parlinska, D. Frey, W. M. Mook et al.
We report on a comprehensive structural and nanoindentation study of nanolaminates of AlO and ZnO synthesized by atomic layer deposition (ALD). By reducing the bilayer thickness from 50 nm to below 1 nm, the nanocrystal size could be controlled in the nanolaminate structure. The softer and more comp ... [Appl. Phys. Lett. 100, 191912 (2012)] published Thu May 10, 2012.

Nanoscale quantification of octahedral tilts in perovskite films

Jinwoo Hwang, Jack Y. Zhang, Junwoo Son, and Susanne Stemmer
NiO-octahedral tilts in ultrathin LaNiO films were studied using position averaged convergent beam electron diffraction (PACBED) in scanning transmission electron microscopy. Both the type and magnitude of the octahedral tilts were determined by comparing PACBED experiments to frozen phonon multisli ... [Appl. Phys. Lett. 100, 191909 (2012)] published Wed May 9, 2012.

Bandgap and band discontinuity in wurtzite/zincblende GaAs homomaterial heterostructure

Ron Gurwitz, Asa Tavor, Liran Karpeles, Ilan Shalish, Wei Yi et al.
A wurtzite GaAs epilayer grown on a zincblende GaAs substrate by metalorganic chemical vapor deposition is studied by surface photovoltage spectroscopy. The wurtzite structure of the epilayer is disclosed by scanning electron microscope images of surface pits, where the pits are seen to change their ... [Appl. Phys. Lett. 100, 191602 (2012)] published Wed May 9, 2012.

High quality factor AlN nanocavities embedded in a photonic crystal waveguide

D. Sam-Giao, D. Neel, S. Sergent, B. Gayral, M. J. Rashid et al.
We present a spectroscopic study of nanocavities obtained by small modifications of a W1 waveguide in an AlN photonic crystal membrane. The AlN film containing GaN quantum dots is grown on silicon. The photonic crystal structure is defined by e-beam lithography and etched by inductively coupled plas ... [Appl. Phys. Lett. 100, 191104 (2012)] published Wed May 9, 2012.

Enhancement of x-rays generated by a guided laser wakefield accelerator inside capillary tubes

J. Ju, K. Svensson, A. Dopp, H. E. Ferrari, K. Cassou et al.
Electrons accelerated in the nonlinear regime in a laser wakefield accelerator experience transverse oscillations inside the plasma cavity, giving rise to ultra-short pulsed x-rays, also called the betatron radiation. We show that the fluence of x-ray can be enhanced by more than one order of magnit ... [Appl. Phys. Lett. 100, 191106 (2012)] published Wed May 9, 2012.

Sub-monolayer quantum dots in confinement enhanced dots-in-a-well heterostructure

S. Sengupta, J. O. Kim, A. V. Barve, S. Adhikary, Y. D. Sharma et al.
We have investigated optical properties and device performance of sub-monolayer quantum dots infrared photodetector with confinement enhancing (CE) barrier and compared with conventional Stranski-Krastanov quantum dots with a similar design. This quantum dots-in-a-well structure with CE barrier enab ... [Appl. Phys. Lett. 100, 191111 (2012)] published Wed May 9, 2012.

Beyond ferromagnetic resonance: The inertial regime of the magnetization

E. Olive, Y. Lansac, and J.-E. Wegrowe
An inertial regime of the magnetization dynamics at short time scales has been recently predicted for uniform magnetization. We study numerically the corresponding generalized Gilbert equation in both the time domain and in the frequency domain. The time dependence shows a typical nutation behavior ... [Appl. Phys. Lett. 100, 192407 (2012)] published Wed May 9, 2012.

Effects of contact space charge on the performance of quantum intersubband photodetectors

A. V. Barve, S. Meesala, S. Sengupta, J. O. Kim, S. Chakrabarti et al.
Highly non-uniform electric field exists in the active region of quantum intersubband devices, primarily due to the presence of PN junctions forming between heavily doped contact regions and non-intentionally doped barriers. Using a combination of experiments and theoretical simulations, we investig ... [Appl. Phys. Lett. 100, 191107 (2012)] published Wed May 9, 2012.

Broadband transmission enhancement of acoustic waves through a hybrid grating

Chunyin Qiu, Rui Hao, Feng Li, Shengjun Xu, and Zhengyou Liu
We report an anomalous transmission enhancement of acoustic waves through a hybrid grating. The fundamental physics behind this phenomenon can be captured well by the improved impedance matching between the hybrid grating and the background fluid. This type of acoustic transparency is broadband and ... [Appl. Phys. Lett. 100, 191908 (2012)] published Wed May 9, 2012.

Distributed hydrogen sensing using in-fiber Rayleigh scattering

Tong Chen, Qingqing Wang, Rongzhang Chen, Botao Zhang, Kevin P. Chen et al.
This letter reports a fully distributed hydrogen sensing technique using Rayleigh backscattering in palladium (Pd) and copper (Cu) coated optical fiber. The local in-fiber strain changes due to Pd hydrogen absorptions are interrogated spatially resolved optical frequency domain reflectrometry measur ... [Appl. Phys. Lett. 100, 191105 (2012)] published Wed May 9, 2012.

Ferromagnetic properties of single walled carbon nanotubes doped with manganese oxide using an electrochemical method

Chang Soo Park, Xiao Zhan Jin, Ki Nam Yun, Young Ran Park, Yoon Shon et al.
We report the ferromagnetic doping of single walled carbon nanotubes (SWCNTs) using an electrochemical method. Ferromagnetism was well defined at the low temperature region and the Curie temperature was above 350 K. The coercive field increases monotonically with the increasing manganese concentrati ... [Appl. Phys. Lett. 100, 192409 (2012)] published Wed May 9, 2012.

Empirical modeling of the cross section of damage formation in ion implanted III-V semiconductors

E. Wendler and L. Wendler
In this letter, the cross section of damage formation per individual ion is measured for III-V compound semiconductors ion implanted at 15 K, applying Rutherford backscattering spectrometry. An empirical model is proposed that explains the measured cross sections in terms of quantities representing ... [Appl. Phys. Lett. 100, 192108 (2012)] published Wed May 9, 2012.

Residual charge density distribution measurement of surface leader with feedback electrostatic probe

Junbo Deng, Akiko Kumada, Kunihiko Hidaka, Guanjun Zhang, and Haibao Mu
A charge density distribution scanning system is fabricated using an electrostatic probe, which utilizes DC voltage feedback principle to nullify the electric field between the probe and charged insulator surface. A two-layer structure pipe is designed to lower the surface potential after discharge. ... [Appl. Phys. Lett. 100, 192906 (2012)] published Wed May 9, 2012.

Electric field control of domain wall propagation in Pt/Co/GdOx films

Uwe Bauer, Satoru Emori, and Geoffrey S. D. Beach
The influence of a gate voltage on domain wall (DW) propagation is investigated in ultrathin Pt/Co/gadolinium oxide (GdOx) films with perpendicular magnetic anisotropy. The DW propagation field can be enhanced or retarded by an electric field at the Co/GdOx interface and scales linearly with gate vo ... [Appl. Phys. Lett. 100, 192408 (2012)] published Wed May 9, 2012.

Waveguide artefacts in terahertz near field imaging

M. Misra, S. R. Andrews, and S. A. Maier
We report experimental and computational studies of the behaviour of a photoconductive THz near field probe when imaging a simple planar metal-dielectric structure. We show that the excitation of waveguide modes in the gap between sample and probe, together with diffraction at the probe, must genera ... [Appl. Phys. Lett. 100, 191109 (2012)] published Wed May 9, 2012.

Enhanced THz emission from c-plane InGaN due to piezoelectric field-induced electron transport

Nathaniel Woodward, C. Gallinat, L. E. Rodak, G. D. Metcalfe, H. Shen et al.
Enhanced terahertz emission from coherently strained InGaN epilayers on GaN is observed, which exceeds or is comparable to bulk InAs emission at pump wavelengths of 400 nm or 800 nm, respectively. The inverted terahertz waveform from the InGaN/GaN heterostructure indicates that the dominant terahert ... [Appl. Phys. Lett. 100, 191110 (2012)] published Wed May 9, 2012.

Spatial control of magnetic anisotropy for current induced domain wall injection in perpendicularly magnetized CoFeB|MgO nanostructures

Masamitsu Hayashi, Michihiko Yamanouchi, Shunsuke Fukami, Jaivardhan Sinha, Seiji Mitani et al.
Magnetic anisotropy of perpendicularly magnetized CoFeB|MgO films is spatially tailored using depth controlled Ar ion etching with patterned etching masks. Nanowires with patterned etching have significantly reduced coercivity compared to those without the etching. We show that the sign of the aniso ... [Appl. Phys. Lett. 100, 192411 (2012)] published Wed May 9, 2012.

Extremely low surface recombination velocities in black silicon passivated by atomic layer deposition

Martin Otto, Matthias Kroll, Thomas Kasebier, Roland Salzer, Andreas Tunnermann et al.
We investigate the optical and opto-electronic properties of black silicon (b-Si) nanostructures passivated with AlO. The b-Si nanostructures significantly improve the absorption of silicon due to superior anti-reflection and light trapping properties. By coating the b-Si nanostructures with a confo ... [Appl. Phys. Lett. 100, 191603 (2012)] published Wed May 9, 2012.

Wavefront corrected light sheet microscopy in turbid media

H. I. C. Dalgarno, T. Cizmar, T. Vettenburg, J. Nylk, F. J. Gunn-Moore et al.
Light sheet microscopy is a powerful method for three-dimensional imaging of large biological specimens. However, its imaging ability is greatly diminished by sample scattering and aberrations. Optical clearing, Bessel light modes, and background rejection have been employed in attempts to circumven ... [Appl. Phys. Lett. 100, 191108 (2012)] published Wed May 9, 2012.

Study of electromagnetic enhancement for surface enhanced Raman spectroscopy of SiC graphene

Jing Niu, Viet Giang Truong, Han Huang, Sudhiranjan Tripathy, Caiyu Qiu et al.
The electromagnetic enhancement for surface enhanced Raman spectroscopy (SERS) of graphene is studied by inserting a layer of AlO between epitaxial graphene and Au nanoparticles. Different excitation lasers are utilized to study the relationship between laser wavelength and SERS. The theoretical cal ... [Appl. Phys. Lett. 100, 191601 (2012)] published Wed May 9, 2012.

Mechanisms of fragmentation of aluminum-tungsten granular composites under dynamic loading

K. L. Olney, V. F. Nesterenko, and D. J. Benson
Numerical simulations of aluminum (Al) and tungsten (W) granular composite rings under various dynamic loading conditions due to explosive loading were performed. Three competing mechanisms of fragmentation were observed: a continuum level mechanism generating macrocracks with a size scale comparabl ... [Appl. Phys. Lett. 100, 191910 (2012)] published Wed May 9, 2012.

Oxygen transport and GeO stability during thermal oxidation of Ge

S. R. M. da Silva, G. K. Rolim, G. V. Soares, I. J. R. Baumvol, C. Krug et al.
Oxygen transport during thermal oxidation of Ge and desorption of the formed Ge oxide are investigated. Higher oxidation temperatures and lower oxygen pressures promote GeO desorption. An appreciable fraction of oxidized Ge desorbs during the growth of a GeO layer. The interplay between oxygen desor ... [Appl. Phys. Lett. 100, 191907 (2012)] published Wed May 9, 2012.

Losses from long-living photoelectrons in terahertz-generating continuous-wave photomixers

E. A. Michael and M. Mikulics
The extraction of continuous-wave terahertz (THz) power from photonic mixers is known to be hampered by input power limitations, low conversion efficiencies, and saturation effects. Using vertically illuminated low-temperature-grown GaAs travelling-wave mixers with a coplanar stripline geometry, a m ... [Appl. Phys. Lett. 100, 191112 (2012)] published Wed May 9, 2012.

High-power 2.0 [mu]m semiconductor disk laserInfluence of lateral lasing

Tino Topper, Marcel Rattunde, Sebastian Kaspar, Rudiger Moser, Christian Manz et al.
The influence of lateral lasing on the high-power performance of 2 [mu]m GaSb-based optically pumped semiconductor disk laser (SDL) has been investigated. The maximum cw output power of the SDL exceeded 4.1 W at 20 degrees C heat sink temperature. The occurrence of lateral lasing was observed by re ... [Appl. Phys. Lett. 100, 192107 (2012)] published Wed May 9, 2012.

Surface acoustic wave in yttrium iron garnet as tunable magnonic crystals for sensors and signal processing applications

R. G. Kryshtal and A. V. Medved
Experimental results on investigation of magnonic crystals arising at surface acoustic wave (SAW) propagation in yttrium iron garnet as an artificial structure for surface magnetostatic waves propagation are presented. Tuning of magnonic gap frequency and gap depth were obtained by changing frequenc ... [Appl. Phys. Lett. 100, 192410 (2012)] published Wed May 9, 2012.

Stochastic processes in light-assisted nanoparticle formation

Makoto Naruse, Yang Liu, Wataru Nomura, Takashi Yatsui, Masaki Aida et al.
Recently, light-assisted nanofabrication have been introduced, such as the synthesis of quantum dots using photo-induced desorption that yields reduced size fluctuations or metal sputtering under light illumination resulting in self-organized, nanoparticle chains. The physical mechanisms have origin ... [Appl. Phys. Lett. 100, 193106 (2012)] published Tue May 8, 2012.

Multi-state resistive switching memory with secure information storage in Au/BiFeMnO/LaCaMnO heterostructure

Y. P. Yao, Y. K. Liu, S. N. Dong, Y. W. Yin, S. W. Yang et al.
The ferroelectric polarization dependent bipolar and conductive filament related unipolar resistive switching behaviors are investigated systematically in Au/BiFeMnO/LaCaMnO heterostructure. The results show that after conductive filaments are formed, the ferroelectric state previously polarized wil ... [Appl. Phys. Lett. 100, 193504 (2012)] published Tue May 8, 2012.

Ultrafast oxygen exchange kinetics on highly epitaxial PrBaCoO thin films

Jian Liu, Gregory Collins, Ming Liu, Chonglin Chen, Jie He et al.
Symmetric half cell structures of highly epitaxial PrBaCoO (PBCO)/GdCeOYZrO/PrBaCoO thin films were designed and fabricated on (001) LaAlO. Microstructural studies indicate that the multilayer films have excellent single-crystal quality and epitaxial nature. The electrochemical impedance spectroscop ... [Appl. Phys. Lett. 100, 193903 (2012)] published Tue May 8, 2012.

Direct and charge transfer state mediated photogeneration in polymerfullerene bulk heterojunction solar cells

M. Mingebach, S. Walter, V. Dyakonov, and C. Deibel
We investigated photogeneration yield and recombination dynamics in blends of poly(3-hexyl thiophene) (P3HT) and poly[2-methoxy-5 -(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) with [6,6]-phenyl-Cbutyric acid methyl ester (PCBM) by means of temperature dependent time delayed collection ... [Appl. Phys. Lett. 100, 193302 (2012)] published Tue May 8, 2012.

Electromechanical behavior of [001]-textured Pb(MgNb)O-PbTiO ceramics

Yongke Yan, Yu. U. Wang, and Shashank Priya
[001]-textured Pb(MgNb)O-PbTiO (PMN-PT) ceramics were synthesized by using templated grain growth method. Significantly high [001] texture degree corresponding to 0.98 Lotgering factor was achieved at 1 vol. % BaTiO template. Electromechanical properties for [001]-textured PMN-PT ceramics with 1 vol ... [Appl. Phys. Lett. 100, 192905 (2012)] published Tue May 8, 2012.

Role of the electric waveform supplying a dielectric barrier discharge plasma actuator

N. Benard and E. Moreau
The paper compares the influence of different waveforms as input for a dielectric barrier discharge plasma actuator investigated in context of plasma-assisted flow control. The electrical aspects, the plasma morphology, the body force production, and the two-component time-resolved electric wind pro ... [Appl. Phys. Lett. 100, 193503 (2012)] published Tue May 8, 2012.

Giant magnetoelectric coupling in laminate thin film structure grown on magnetostrictive substrate

Chee-Sung Park, Armen Khachaturyan, and Shashank Priya
Highly dense 1 [mu]m-thick piezoelectric film was deposited on magnetostrictive substrate [platinized nickel-zinc ferrite (NZF)]. A strong magnetic coupling between the piezoelectric film and magnetostrictive NZF substrate was measured exhibiting the maximum magnetoelectric (ME) coefficient on the o ... [Appl. Phys. Lett. 100, 192904 (2012)] published Tue May 8, 2012.

Flow and force inducement using micron size dielectric barrier discharge actuators

Justin C. Zito, Ryan J. Durscher, Jignesh Soni, Subrata Roy, and David P. Arnold
Micron size dielectric barrier discharge actuators, designed for minimal footprint area and weight penalty, show a wall jet up to 2.0 m/s consuming 15 W/m of electrode. A torsional balance measures force up to 3 mN/m of electrode and demonstrates equivalent thrust effectiveness (induced force/power) ... [Appl. Phys. Lett. 100, 193502 (2012)] published Tue May 8, 2012.

Turn-on spread determines the size of the switching region in an avalanche transistor

Guoyong Duan, Sergey Vainshtein, and Juha Kostamovaara
It has been shown recently that only a small part of the emitter-base interface in a Si bipolar junction transistor participates in short-pulsing avalanche switching. This lateral current shrinkage attributed to the winner takes all effect reduces the transistor switching size from 1600 to ~100 [mu] ... [Appl. Phys. Lett. 100, 193505 (2012)] published Tue May 8, 2012.

Raman analysis of monoclinic CuSnS thin films

Dominik M. Berg, Rabie Djemour, Levent Gutay, Susanne Siebentritt, Phillip J. Dale et al.
Secondary phases like CuSnS are major obstacles for kesterite thin film solar cell applications. We prepare CuSnS using identical annealing conditions as used for the kesterite films. By x-ray diffraction, the crystal structure of CuSnS was identified as monoclinic. Polarization-dependent Raman inve ... [Appl. Phys. Lett. 100, 192103 (2012)] published Tue May 8, 2012.

Antiferromagnetic domain wall engineering in chromium films

J. M. Logan, H. C. Kim, D. Rosenmann, Z. Cai, R. Divan et al.
We have engineered an antiferromagnetic domain wall by utilizing a magnetic frustration effect of a thin iron cap layer deposited on a chromium film. Through lithography and wet etching, we selectively remove areas of the Fe cap layer to form a patterned ferromagnetic mask over the Cr film. Removing ... [Appl. Phys. Lett. 100, 192405 (2012)] published Tue May 8, 2012.

Defect and adsorbate induced ferromagnetic spin-order in magnesium oxide nanocrystallites

Ashok Kumar, Jitendra Kumar, and Shashank Priya
We report the correlation between d ferromagnetism, photoluminescence (PL), and adsorbed hydrogen (H) species in magnesium oxide (MgO) nanocrystallites. Our study suggests that the oxygen vacancies, namely singly ionized anionic vacancies (F) and dimers (F) induce characteristic photoluminescence an ... [Appl. Phys. Lett. 100, 192404 (2012)] published Tue May 8, 2012.

Optimization of AlAs/AlGaAs quantum well heterostructures on on-axis and misoriented GaAs (111)B

F. Herzog, M. Bichler, G. Koblmuller, S. Prabhu-Gaunkar, W. Zhou et al.
We report systematic growth optimization of high Al-content AlGaAs, AlAs, and associated modulation-doped quantum well (QW) heterostructures on on-axis and misoriented GaAs (111)B by molecular beam epitaxy. Growth temperatures T > 690 degrees C and low As fluxes close to group III-rich growth signi ... [Appl. Phys. Lett. 100, 192106 (2012)] published Tue May 8, 2012.

Grating duty-cycle induced enhancement of substrate emission from ring cavity quantum cascade lasers

Clemens Schwarzer, Elvis Mujagic, Sang Il Ahn, Aaron Maxwell Andrews, Werner Schrenk et al.
We report on experimental and theoretical investigation of grating parameters to promote one specific emission direction from ring-cavity quantum cascade lasers. The devices show single-mode behavior at room temperature and pulsed operation. A maximized surface output power was found for grating dut ... [Appl. Phys. Lett. 100, 191103 (2012)] published Tue May 8, 2012.

Millimeter wave transmission spectroscopy of gated two-dimensional hole systems

K. Stone, R. R. Du, M. J. Manfra, L. N. Pfeiffer, and K. W. West
We developed a differential transmission to study cyclotron resonance of GaAs/AlGaAs two-dimensional hole samples. The technique utilizes a modulated AuPd gate isolated by a Si N dielectric from the sample, which is irradiated opposite the gate by millimeter waves ranging from 2 to 40 GHz. This tech ... [Appl. Phys. Lett. 100, 192104 (2012)] published Tue May 8, 2012.

In situ microwave characterization of microwire composites with external magnetic field

F. X. Qin, C. Brosseau, H. X. Peng, H. Wang, and J. Sun
Rubber composites containing CoFeSiB glass-covered amorphous microwires were fabricated. For samples containing 5 mm long wires and randomly dispersed in the polymer matrix, our results demonstrate that the current induces resonance of circumferential permeability (magnetoimpedance resonance) result ... [Appl. Phys. Lett. 100, 192903 (2012)] published Tue May 8, 2012.

Low-temperature, site selective graphitization of SiC via ion implantation and pulsed laser annealing

Maxime G. Lemaitre, Sefaattin Tongay, Xiaotie Wang, Dinesh K. Venkatachalam, Joel Fridmann et al.
A technique is presented to selectively graphitize regions of SiC by ion implantation and pulsed laser annealing (PLA). Nanoscale features are patterned over large areas by multi-ion beam lithography and subsequently converted to few-layer graphene via PLA in air. Graphitization occurs only where io ... [Appl. Phys. Lett. 100, 193105 (2012)] published Tue May 8, 2012.

Optical phonon lifetimes in sputtered AlN thin films

P. Pobedinskas, B. Ruttens, J. D'Haen, and K. Haenen
We study the vibrational properties of AlN thin films deposited on silicon (100) substrates by the reactive DC-pulsed magnetron sputtering. The frequencies and lifetimes of the E(TO) and A(LO) optical phonons are calculated from Fourier transform infrared spectra using the factorized model of a damp ... [Appl. Phys. Lett. 100, 191906 (2012)] published Tue May 8, 2012.

Spin-polarized two-dimensional electron gas in undoped MgZnO/ZnO heterostructures

K. Han, N. Tang, J. D. Ye, J. X. Duan, Y. C. Liu et al.
Quantum transport properties of two-dimensional electron gas (2DEG) in undoped MgZnO/ZnO heterostructures grown by metal organic vapor phase epitaxy have been investigated. A large zero-field spin-splitting energy more than 15 meV in the 2DEG is determined at 1.6 K. Meanwhile, ferromagnetism is obse ... [Appl. Phys. Lett. 100, 192105 (2012)] published Tue May 8, 2012.

Low temperature fabrication and characterization of nickel germanide Schottky source/drain contacts for implant-less germanium p-channel metal-oxide-semiconductor field-effect transistors

D. R. Gajula, D. W. McNeill, B. E. Coss, H. Dong, S. Jandhyala et al.
In this work, nickel germanide Schottky contacts have been fabricated on n-type germanium (n-Ge) with an optimum barrier height of 0.63 eV. For rapid thermal annealing (RTA) temperatures above 300 degrees C, all phases of nickel and germanium convert to nickel mono-germanide (NiGe). However, highe ... [Appl. Phys. Lett. 100, 192101 (2012)] published Tue May 8, 2012.

Real-time x-ray diffraction of metastable phases during solidification from the undercooled LuFeO melt by two-dimensional detector at 1 kHz

Malahalli Vijaya Kumar, K. Kuribayashi, K. Nagashio, T. Ishikawa, J. Okada et al.
In-situ identification of metastable phases formed from the undercooled LuFeO melt under controlled oxygen partial pressure Po was studied by x-ray diffraction measurements at a synchrotron radiation source. Real-time observation of the formation and growth of individual phases during the single rec ... [Appl. Phys. Lett. 100, 191905 (2012)] published Tue May 8, 2012.

Magnetic vortices in single crystalline Fe-V disks with four folds magnetic anisotropy

K. Mitsuzuka, D. Lacour, M. Hehn, S. Andrieu, and F. Montaigne
Magnetic vortices in circular disks made from Fe-V single crystal film have been studied by magnetic force microscopy. At remanent state, all the disks host a single vortex structure. The magnetic contrast differs drastically from the one usually observed in "traditional" materials and reveals the i ... [Appl. Phys. Lett. 100, 192406 (2012)] published Tue May 8, 2012.

Non-volatile organic memory devices comprising SiO and C showing 10 switching cycles

P. Siebeneicher, H. Kleemann, K. Leo, and B. Lussem
We present a non-volatile organic memory device comprising a thin SiO layer, the organic semiconductor C, and an organic n-type doped layer between two metallic electrodes. The memory device shows a stable hysteresis in the current-voltage characteristics with an ON/OFF ratio in the range of three o ... [Appl. Phys. Lett. 100, 193301 (2012)] published Tue May 8, 2012.

Flexible thin-film InAs/GaAs quantum dot solar cells

Katsuaki Tanabe, Katsuyuki Watanabe, and Yasuhiko Arakawa
Thin-film InAs/GaAs quantum dot (QD) solar cells on mechanically flexible plastic films are fabricated. A 4.1-[mu]m-thick compound semiconductor photovoltaic layer grown on a GaAs substrate is transferred onto a plastic film through a low-temperature bonding technique. We also fabricate thin-film In ... [Appl. Phys. Lett. 100, 192102 (2012)] published Tue May 8, 2012.

Method to determine hkl strains and shear moduli under torsion using neutron diffraction

R. Woracek, J. R. Bunn, D. Penumadu, and C. R. Hubbard
An experimental method, using in-situ neutron diffraction for the measurement of shear strain, based on (hkl) lattice spacing changes under torsional loading, is described. This method provides the ability to probe the response of crystallographic planes to application of shear stress, inside the bu ... [Appl. Phys. Lett. 100, 191904 (2012)] published Tue May 8, 2012.

Optimizing fiber cross-sectional shape for improving stability of airwater interface over superhydrophobic fibrous coatings

B. Emami and H. Vahedi Tafreshi
In this letter, a mathematical force-balance formulation is developed that can be used to predict the critical pressure, the hydrostatic pressure above which the surface starts to depart from the non-wetting state, for superhydrophobic surfaces comprised of highly aligned fibers (e.g., biased AC-ele ... [Appl. Phys. Lett. 100, 193104 (2012)] published Mon May 7, 2012.

Erratum: Microwave-absorption properties of ZnO-coated iron nanocapsules [Appl. Phys. Lett. 92, 173117 (2008)]

X. G. Liu, D. Y. Geng, H. Meng, P. J. Shang, and Z. D. Zhang
Abstract not available. [Appl. Phys. Lett. 100, 199902 (2012)] published Mon May 7, 2012.

Erratum: `Water-cycle' mechanism for writing and erasing nanostructures at the LaAlO/SrTiO interface [Appl. Phys. Lett. 97, 173110 (2010)]

Feng Bi, Daniela F. Bogorin, Cheng Cen, Chung Wung Bark, Jae-Wan Park et al.
Abstract not available. [Appl. Phys. Lett. 100, 199901 (2012)] published Mon May 7, 2012.

Erratum: A model for the band gap energy of the N-rich GaNAs (0 <= x <= 0.07) [Appl. Phys. Lett. 100, 142112 (2012)]

Chuan-Zhen Zhao, Na-Na Li, Tong Wei, Chun-Xiao Tang, and Ke-Qing Lu
Abstract not available. [Appl. Phys. Lett. 100, 199903 (2012)] published Mon May 7, 2012.

Hydrogen release from Li alanates originates in molecular lattice instability emerging at ~100 K

K. Tomiyasu, T. Sato, K. Horigane, S. Orimo, and K. Yamada
Lattice vibrations from 20 K to room temperature in lithium alanates LiAlH and LiAlH, which decompose to release hydrogen over 423 K, were investigated by neutron spectroscopy. For both alanates, the overall spectra already start to broaden at 100150 K with increasing temperature. The spectral lines ... [Appl. Phys. Lett. 100, 193901 (2012)] published Mon May 7, 2012.

Improving the quality factor of microwave compact resonators by optimizing their geometrical parameters

K. Geerlings, S. Shankar, E. Edwards, L. Frunzio, R. J. Schoelkopf et al.
Applications in quantum information processing and photon detectors are stimulating a race to produce the highest possible quality factor on-chip superconducting microwave resonators. We have tested the surface-dominated loss hypothesis by systematically studying the role of geometrical parameters o ... [Appl. Phys. Lett. 100, 192601 (2012)] published Mon May 7, 2012.

Influence of the nonlinear dynamic plasma screening on the electron-dust collision in dusty plasmas

Dae-Han Ki and Young-Dae Jung
The nonlinear dynamic plasma screening effects on the elastic electron-dust grain collision are investigated in dusty plasmas. The results show that the nonlinear dynamic screening effect significantly increases the magnitude of the eikonal phase shift. It is also found that the magnitude of the pha ... [Appl. Phys. Lett. 100, 194102 (2012)] published Mon May 7, 2012.

Photo-induced changes in fundamental properties of organic solar cells

J. Bhattacharya, R. W. Mayer, M. Samiee, and V. L. Dalal
We report on the measurement of fundamental properties such as deep defects and hole mobility in poly-3-hexyl-thiophene (P3HT)/[6,6]-phenyl-C60-butyric acid methyl ester(PCBM) solar cells when the cells are exposed to solar radiation without any atmospheric exposure. It is found that the midgap defe ... [Appl. Phys. Lett. 100, 193501 (2012)] published Mon May 7, 2012.

Reduction of spectral phonon relaxation times from suspended to supported graphene

Bo Qiu and Xiulin Ruan
We have performed molecular dynamics simulations with phonon spectral analysis to predict the mode-wise phonon relaxation times (RT) of suspended and supported graphene at room temperature, and the findings are consistent with recent optical measurements. For acoustic phonons, RTs reduce from up to ... [Appl. Phys. Lett. 100, 193101 (2012)] published Mon May 7, 2012.

An efficient way to enhance output strain for shear mode Pb(InNb)O-Pb(MgNb)O-PbTiO crystals: Applying uniaxial stress perpendicular to polar direction

Fei Li, Shujun Zhang, Zhuo Xu, Dabin Lin, JunJie Gao et al.
The shear piezoelectric behavior of [001] poled tetragonal and [011] poled rhombohedral Pb(InNb)O-Pb(MgNb)O-PbTiO (PIN-PMN-PT) crystals, with 1T and 2R domain configurations, respectively, were investigated under uniaxial stress perpendicular to polar direction. The shear piezoelectric coefficient d ... [Appl. Phys. Lett. 100, 192901 (2012)] published Mon May 7, 2012.

Electron energy-loss spectroscopy study of MgH in the plasmon energy range

B. Paik, A. Walton, V. Mann, D. Book, I. P. Jones et al.
Electron energy loss spectroscopy of MgH in the plasmon energy range is reported here as a part of a study to determine the dielectric function of this hydride. From the dielectric function, we have estimated the unperturbed plasmon energy of MgH as 11.34 eV. Interband transitions are also inferred ... [Appl. Phys. Lett. 100, 193902 (2012)] published Mon May 7, 2012.

Intrinsic electrocaloric effect in ultrathin ferroelectric capacitors

Yang Liu, Xing-ping Peng, Xiaojie Lou, and Hu Zhou
Electrocaloric effect in ultrathin SrRuO/BaTiO/SrRuO capacitors is calculated using a multiscale thermodynamic model. It is found that the electrocaloric coefficient vs working temperature is shifted to higher temperatures with increasing the BaTiO layer thickness (above the critical thickness). The ... [Appl. Phys. Lett. 100, 192902 (2012)] published Mon May 7, 2012.

Nanoscale integration of SiC/SiO core-shell nanocables in diamond through a simultaneous hybrid structure fabrication

Hao Zhuang, Lei Zhang, Thorsten Staedler, and Xin Jiang
The nanoscale integration of SiC nanocables in a diamond thin film is achieved through a novel synthetic pathway, which combines Fe catalyst and detonation nanodiamond seeding technique in a microwave plasma chemical vapor deposition process. The obtained hybrid structures show controllable SiC nano ... [Appl. Phys. Lett. 100, 193102 (2012)] published Mon May 7, 2012.

Enhanced sheath heating in capacitively coupled discharges due to non-sinusoidal voltage waveforms

T. Lafleur, R. W. Boswell, and J. P. Booth
Through the use of particle-in-cell simulations, we demonstrate that the power deposition in capacitively coupled discharges (in argon) can be increased by replacing sinusoidal waveforms with Gaussian-shaped voltage pulses (with a repetition frequency of 13.56 MHz). By changing the Gaussian pulse wi ... [Appl. Phys. Lett. 100, 194101 (2012)] published Mon May 7, 2012.

Schottky solar cells based on graphene nanoribbon/multiple silicon nanowires junctions

Chao Xie, Jiansheng Jie, Biao Nie, Tianxin Yan, Qiang Li et al.
We report the construction of Schottky solar cells based on graphene nanoribbon/multiple silicon nanowires (SiNWs) junctions. Only a few (~10) SiNWs were involved to miniaturize the solar cell for nanoscale power source applications. It was found that doping level of the SiNWs played an important ro ... [Appl. Phys. Lett. 100, 193103 (2012)] published Mon May 7, 2012.

Rate dependence of the serrated flow in Ni-10Pd during high temperature instrumented microindentation

Bin Gan and Sammy Tin
Instrumented indentation tests were conducted on a pure nickel and a Ni-10Pd solid solution at 450 degrees C with loading rates varying from 62.5 to 1000 mN/s. The loaddepth curves from the pure nickel exhibited a smooth and continuous transition; while the loaddepth curves from the Ni-10Pd were in ... [Appl. Phys. Lett. 100, 191902 (2012)] published Mon May 7, 2012.

On the practicability of pentamode mechanical metamaterials

Muamer Kadic, Tiemo Buckmann, Nicolas Stenger, Michael Thiel, and Martin Wegener
Conceptually, all conceivable three-dimensional mechanical materials can be built from pentamode materials. Pentamodes also enable to implement three-dimensional transformation elastodynamicsthe analogue of transformation optics. However, pentamodes have not been realized experimentally. Here, we in ... [Appl. Phys. Lett. 100, 191901 (2012)] published Mon May 7, 2012.

Growth rate and start current in SmithPurcell free-electron lasers

D. Li (李大治), M. Hangyo, Y. Tsunawaki, Z. Yang, Y. Wei et al.
This letter reports a theory to calculate the growth rate and start current of a SmithPurcell free-electron laser, which is a promising radiation source in the terahertz domain. A two-dimensional model was used to investigate the interaction between a sheet electron beam and the surface wave above a ... [Appl. Phys. Lett. 100, 191101 (2012)] published Mon May 7, 2012.

Analysis of intermolecular interaction of poly(N-isopropylacrylamide) solution with attenuated total reflectance terahertz spectroscopy

H. Naito, Y. Ogawa, H. Hoshina, S. Sultana, and N. Kondo
The terahertz attenuated total reflectance spectra of Poly(N-isopropylacrylamide) (P-NIPAAm) solutions were measured in the range of 26.547.3 degrees C. The phase-change in P-NIPAAm was observed via the temperature dependence of the spectra. The collapse of hydrogen bonds in solution was confirmed ... [Appl. Phys. Lett. 100, 191102 (2012)] published Mon May 7, 2012.

The comparison of direct and indirect methods for determining the magnetocaloric parameters in the Heusler alloy NiMnInB

Igor Dubenko, Tapas Samanta, Abdiel Quetz, Alexander Kazakov, Igor Rodionov et al.
The magnetocaloric properties of the NiMnInB Heusler alloy have been studied by direct measurements of the adiabatic temperature change (DeltaT(T,H)) and indirectly by magnetization (M(T,H)), differential scanning calorimetry, and specific heat (C(T,H)) measurements. The presence of a first-order fe ... [Appl. Phys. Lett. 100, 192402 (2012)] published Mon May 7, 2012.

Spin-polarization of VO center in GaN and its application in spin qubit

Xiaopeng Wang, Mingwen Zhao, Zhenhai Wang, Xiujie He, Yan Xi et al.
VO center in cubic gallium nitride is a defect complex composing of a substitutional oxygen atom at nitrogen site (O) and an adjacent gallium vacancy (V). Based on first-principles calculations, we predicted that this VO center has much in common with the famous nitrogen-vacancy center in diamond, b ... [Appl. Phys. Lett. 100, 192401 (2012)] published Mon May 7, 2012.

Generation and annihilation of domain walls in nanowires by localized fields

Falk-Ulrich Stein, Lars Bocklage, Toru Matsuyama, and Guido Meier
We study the creation and annihilation of domain walls in a permalloy nanowire by local Oersted fields of current pulses passing through a perpendicularly aligned stripline. The occurrence of both processes is investigated for current pulses of different polarities and for various external magnetic ... [Appl. Phys. Lett. 100, 192403 (2012)] published Mon May 7, 2012.

Generation of acoustic pulses from a photo-acoustic transducer measured by time-resolved x-ray diffraction

Yuan Gao and Matthew F. DeCamp
Picosecond acoustic pulses generated by ultrafast optical excitation of a 100 nm gold photo-acoustic transducer deposited on a germanium substrate are observed using time-resolved x-ray diffraction. The resulting pump-probe spectra reveal that the spatiotemporal structure of the acoustic pulse is bi ... [Appl. Phys. Lett. 100, 191903 (2012)] published Mon May 7, 2012.

Room temperature single GaN nanowire spin valves with FeCo/MgO tunnel contacts

Hyun Kum, Junseok Heo, Shafat Jahangir, Animesh Banerjee, Wei Guo et al.
We report the direct measurement of spin transport characteristics in a GaN spin valve, with a relatively defect-free single GaN nanowire (NW) as the channel and FeCo/MgO as the tunnel barrier spin contact. Hanle spin precession and non-local transport measurements are made in an unintentionally dop ... [Appl. Phys. Lett. 100, 182407 (2012)] published Fri May 4, 2012.

Li-doped BC sheet for high-capacity hydrogen storage

Zailin Yang and Jun Ni
Hydrogen storage on Li-doped BC sheet is studied by the first principles calculations. The Li atoms can be strongly adsorbed on the BC sheet without clustering. For one Li atom adsorbed on the (2 x 2) BC supercell, each Li atom could adsorb four hydrogen molecules. By adsorbing Li atoms on both si ... [Appl. Phys. Lett. 100, 183109 (2012)] published Fri May 4, 2012.

Temperature dependence of frequency response characteristics in organic field-effect transistors

Xubing Lu, Takeo Minari, Chuan Liu, Akichika Kumatani, J.-M. Liu et al.
The frequency response characteristics of semiconductor devices play an essential role in the high-speed operation of electronic devices. We investigated the temperature dependence of dynamic characteristics in pentacene-based organic field-effect transistors and metal-insulator-semiconductor capaci ... [Appl. Phys. Lett. 100, 183308 (2012)] published Fri May 4, 2012.

Optically recorded tunable microlenses based on dye-doped liquid crystal cells

Liana Lucchetti and Jordanka Tasseva
We report on optically recorded microlenses in conventional liquid crystal cells doped with the azo-dye methyl-red. The focal length can be tuned electrically and changed in a wide range with just a small variation of the applied dc voltage. No patterned electrodes, built-in polymeric lens, or patte ... [Appl. Phys. Lett. 100, 181111 (2012)] published Fri May 4, 2012.

Vortex mode dynamics and bandwidth tunability in a two-dimensional array of interacting magnetic disks

Federico Montoncello and Loris Giovannini
We calculate the spin wave spectrum and band diagram of a planar array of interacting disks in the vortex state at zero and finite applied field. We found that the circular polarization of modes depends on the Bloch wavevector k, and that the apparent spin wave profile can change as k increases from ... [Appl. Phys. Lett. 100, 182406 (2012)] published Fri May 4, 2012.

A liftoff process of GaN layers and devices through nanoporous transformation

Yu Zhang, Benjamin Leung, and Jung Han
A process to slice and separate GaN device layers for vertical light emitting diodes (LEDs) is presented through a developed electrochemical anodization process to create nanoporous (NP) GaN of designed porosity profiles. The NP GaN serves dual purposes of supporting subsequent overgrowth of LED str ... [Appl. Phys. Lett. 100, 181908 (2012)] published Fri May 4, 2012.

Electron heating mode transition induced by ultra-high frequency in atmospheric microplasmas for biomedical applications

H. C. Kwon, I. H. Won, and J. K. Lee
The electron heating mode transition induced by ultra-high frequency in atmospheric-pressure microplasmas was investigated using particle-in-cell simulation with a Monte Carlo collision. Interestingly, this discharge mode transition is accompanied by non-monotonic evolution of electron kinetics such ... [Appl. Phys. Lett. 100, 183702 (2012)] published Fri May 4, 2012.

Schottky barrier inhomogeneities at the interface of few layer epitaxial graphene and silicon carbide

Shriram Shivaraman, Lihong H. Herman, Farhan Rana, Jiwoong Park, and Michael G. Spencer
In this work, we study electron transport across the heterojunction interface of epitaxial few-layer graphene grown on silicon carbide and the underlying substrate. The observed Schottky barrier is characterized using current-voltage, capacitance-voltage and photocurrent spectroscopy techniques. It ... [Appl. Phys. Lett. 100, 183112 (2012)] published Fri May 4, 2012.

In-situ oxygen x-ray absorption spectroscopy investigation of the resistance modulation mechanism in LiNbO memristors

Jordan D. Greenlee, Cole F. Petersburg, W. Laws Calley, Cherno Jaye, Daniel A. Fischer et al.
In situ near edge x-ray absorption fine structure spectroscopy (NEXAFS) is performed on LiNbO analog memristors to identify the underlying analog resistance modulation mechanism. Empty electronic state gradients in the NEXAFS difference spectra are observed in biased devices indicating a gradual mov ... [Appl. Phys. Lett. 100, 182106 (2012)] published Fri May 4, 2012.

Nonlinear phonon transport and ballistic thermal rectification in asymmetric graphene-based three terminal junctions

Zhong-Xiang Xie, Ke-Min Li, Li-Ming Tang, Chang-Ning Pan, and Ke-Qiu Chen
By using the nonequilibrium Green's function and the Landauer transport theory, nonlinear phonon properties in asymmetric graphene-based three terminal junctions (AGTTJs) are investigated. Results show that AGTTJs exhibit pronounced nonlinear thermal rectifying behaviors, and the efficiency is effic ... [Appl. Phys. Lett. 100, 183110 (2012)] published Fri May 4, 2012.

Tesla coil discharges guided by femtosecond laser filaments in air

Yohann Brelet, Aurelien Houard, Leonid Arantchouk, Benjamin Forestier, Yi Liu et al.
A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the ... [Appl. Phys. Lett. 100, 181112 (2012)] published Fri May 4, 2012.

Single mode phonon scattering at carbon nanotube-graphene junction in pillared graphene structure

Jonghoon Lee, Vikas Varshney, Joshua S. Brown, Ajit K. Roy, and Barry L. Farmer
Phonon scattering at the carbon nanotube-graphene interface is studied in the pillared graphene structure, using the phonon wave packet method. Qualitatively different scattering characteristics, compared to previous studies of carbon nanotube systems, are observed. The phonon group velocity, dictat ... [Appl. Phys. Lett. 100, 183111 (2012)] published Fri May 4, 2012.