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4 Jun 2012

Volume 100, Issue 23, Articles (23xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 233103 (2012); http://dx.doi.org/10.1063/1.3703763 (4 pages)

Vibhor Singh, Bushra Irfan, Ganesh Subramanian, Hari S. Solanki, Shamashis Sengupta, Sudipta Dubey, Anil Kumar, S. Ramakrishnan, and Mandar M. Deshmukh
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Electrically pumped wavelength-tunable blue random lasing from CdZnO films on silicon

Ye Tian, Xiangyang Ma, Lu Jin, Dongsheng Li, and Deren Yang

Appl. Phys. Lett. 100, 231101 (2012); http://dx.doi.org/10.1063/1.4725486 (4 pages)

Online Publication Date: 4 June 2012

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Electrically pumped lasing actions from the metastable CdZnO films have hardly been achieved as yet. Herein, we have demonstrated electrically pumped wavelength-tunable blue random lasing from the hexagonal CdZnO films with different Cd contents, with central wavelength changing from ∼490 to 425 nm. The devices based on the metal-insulator-semiconductor structures of Au/SiO2/CdZnO on silicon substrates are constructed for electrical pumping of the CdZnO films. The insulator layers of SiO2 onto the CdZnO films in the devices should be annealed at sufficiently low temperature such as 400 °C so that the CdZnO films can be kept their integrity in terms of near-band-edge emissions.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Fc Modulation, tuning, and mode locking

Controlled addressing of quantum dots by nanowire plasmons

Christian Gruber, Primoz Kusar, Andreas Hohenau, and Joachim R. Krenn

Appl. Phys. Lett. 100, 231102 (2012); http://dx.doi.org/10.1063/1.4725490 (3 pages) | Cited 5 times

Online Publication Date: 4 June 2012

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We demonstrate optical near field coupling of small quantum dot (QD) ensembles and surface plasmons propagating along a silver nanowire. The nanowire fabrication and the aligned QD deposition close to one nanowire end rely on a two-step electron beam lithography procedure. We observe both the addressing of QDs by plasmons and the excitation of plasmonic nanowire modes by QDs. We use the fluorescence signals to quantify the QD/plasmon coupling and show that part of the plasmon-induced QD fluorescence couples back to plasmonic modes.
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78.67.Hc Quantum dots
81.16.Nd Micro- and nanolithography
78.55.-m Photoluminescence, properties and materials
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.67.Uh Nanowires
81.07.Gf Nanowires

InGaP microdisk optical resonators embedded in indium tin oxide

Shu-Yu Su and Tomoyuki Yoshie

Appl. Phys. Lett. 100, 231103 (2012); http://dx.doi.org/10.1063/1.4726043 (4 pages)

Online Publication Date: 4 June 2012

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InGaP microdisk optical resonators are embedded in indium tin oxide (ITO) to investigate how the optical absorption in electrodes impacts the resonance properties. The quality factor is slightly reduced in comparison with air-embedding microdisks, and the measured quality factor is 960 for a 1.2 μm diameter, 170 nm thick disk embedded in ITO media. The experiments show that the absorption loss in ITO media has smaller contribution to the reduction of total quality factor than the scattering and radiation losses. The analysis indicates that the suppression of non-absorption loss would improve the quality factor to 104.
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42.79.-e Optical elements, devices, and systems
42.25.Bs Wave propagation, transmission and absorption

A high-resolution spectrometer based on a compact planar two dimensional photonic crystal cavity array

Xuetao Gan, Nadia Pervez, Ioannis Kymissis, Fariba Hatami, and Dirk Englund

Appl. Phys. Lett. 100, 231104 (2012); http://dx.doi.org/10.1063/1.4724177 (4 pages) | Cited 3 times

Online Publication Date: 4 June 2012

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We demonstrate a compact spectrometer based on an array of high-quality-factor photonic crystal nanocavities, coupled via a planar two-dimensional waveguide. This architecture enables spectral analysis of incident light with resolution as high as the bandwidth of the cavity mode–0.3 nm at 840 nm for our device. The design is easily extended to the visible and deep-infrared spectral ranges. The two-dimensional cavity array can be mated to commercial two-dimensional optical detector arrays, creating a compact and high-resolution spectrometer suitable for a range of applications including materials and chemical analysis.
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07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
42.82.Et Waveguides, couplers, and arrays
42.70.Qs Photonic bandgap materials

Electrowetting-driven variable-focus microlens on flexible surfaces

Chenhui Li and Hongrui Jiang

Appl. Phys. Lett. 100, 231105 (2012); http://dx.doi.org/10.1063/1.4726038 (4 pages) | Cited 2 times

Online Publication Date: 5 June 2012

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We demonstrate a flexible, electrowetting-driven, variable-focus liquid microlens. The microlens is fabricated using a soft polymer polydimethylsiloxane. The lens can be smoothly wrapped onto a curved surface. A low-temperature fabrication process was developed to reduce the stress on and to avoid any damage to the polymer. The focal length of the microlens varies between −15.0 mm to +28.0 mm, depending on the applied voltage. The resolving power of the microlens is 25.39 line pairs per mm using a 1951 United States Air Force resolution chart. The typical response time of the lens is around 50 ms.
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42.79.Bh Lenses, prisms and mirrors
42.82.Cr Fabrication techniques; lithography, pattern transfer

Transport of indirect excitons in a potential energy gradient

J. R. Leonard, M. Remeika, M. K. Chu, Y. Y. Kuznetsova, A. A. High, L. V. Butov, J. Wilkes, M. Hanson, and A. C. Gossard

Appl. Phys. Lett. 100, 231106 (2012); http://dx.doi.org/10.1063/1.4722938 (4 pages) | Cited 1 time

Online Publication Date: 5 June 2012

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We realized a potential energy gradient—a ramp—for indirect excitons using a shaped electrode at constant voltage. We studied transport of indirect excitons along the ramp and observed that the exciton transport distance increases with increasing density and temperature.
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71.35.-y Excitons and related phenomena
73.21.Fg Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

All-optical tuning of a quantum dot in a coupled cavity system

Ranojoy Bose, Tao Cai, Glenn S. Solomon, and Edo Waks

Appl. Phys. Lett. 100, 231107 (2012); http://dx.doi.org/10.1063/1.4719065 (4 pages) | Cited 1 time

Online Publication Date: 5 June 2012

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We demonstrate a method for tuning a semiconductor quantum dot (QD) onto resonance with a cavity mode all-optically using a system comprised of two evanescently coupled cavities containing a single QD. One resonance of the coupled cavity system is utilized to generate a cavity enhanced optical Stark shift, enabling the QD to be resonantly tuned to the other cavity mode. A twenty-seven fold increase in photon emission from the QD is measured when the off-resonant QD is Stark shifted onto the cavity mode resonance, which is attributed to radiative enhancement of the QD. A maximum tuning of 0.06 nm is achieved for the QD at an incident power of 88 μW.
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42.70.Qs Photonic bandgap materials
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.67.Hc Quantum dots

Terahertz multichannel microfluidic sensor based on parallel-plate waveguide resonant cavities

Victoria Astley, Kimberly S. Reichel, Jonathan Jones, Rajind Mendis, and Daniel M. Mittleman

Appl. Phys. Lett. 100, 231108 (2012); http://dx.doi.org/10.1063/1.4724204 (4 pages) | Cited 2 times

Online Publication Date: 5 June 2012

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We demonstrate a terahertz multichannel microfluidic sensor based on a parallel-plate waveguide geometry with two independent integrated resonant cavities. The resonant frequency of each cavity exhibits an approximately linear dependence on the index of refraction of the material inside the cavity and each cavity is demonstrated to respond independently with no measurable crosstalk. The sensitivities of the two cavities in terms of the change in resonant wavelength per refractive index unit (RIU) are measured to be 1.21 × 106 nm/RIU and 6.77 × 105 nm/RIU.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
47.80.-v Instrumentation and measurement methods in fluid dynamics
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.40.Az Waveguides, transmission lines, striplines
07.10.Cm Micromechanical devices and systems

Quantitative analysis and near-field observation of strong coupling between plasmonic nanogap and silicon waveguides

Rafael Salas-Montiel, Aniello Apuzzo, Cécile Delacour, Zohreh Sedaghat, Aurélien Bruyant, Philippe Grosse, Alexei Chelnokov, Gilles Lerondel, and Sylvain Blaize

Appl. Phys. Lett. 100, 231109 (2012); http://dx.doi.org/10.1063/1.4725511 (4 pages) | Cited 2 times

Online Publication Date: 6 June 2012

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We present a near field optical study of a plasmonic gap waveguide vertically integrated on silicon. The experimental study is based on a near field scanning optical microscope configured in perturbation mode. This operation mode is described and modeled to give a physical insight into the measured signal. A high spatial resolution allows for the characteristics of the plasmonic gap modes, such as near field distributions, effective indices, direction of propagation, and coupling between perpendicularly polarized modes, to be imaged and analyzed with accuracy. This experimental work is supported by numerical simulations based on finite element optical mode solvers and by the application of the strongly coupled-mode theory to the device.
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42.82.Et Waveguides, couplers, and arrays

Influence of polarity on carrier transport in semipolar (20math) and (20math1) multiple-quantum-well light-emitting diodes

Yoshinobu Kawaguchi, Chia-Yen Huang, Yuh-Renn Wu, Qimin Yan, Chih-Chien Pan, Yuji Zhao, Shinichi Tanaka, Kenji Fujito, Daniel Feezell, Chris G. Van de Walle, Steven P. DenBaars, and Shuji Nakamura

Appl. Phys. Lett. 100, 231110 (2012); http://dx.doi.org/10.1063/1.4726106 (4 pages) | Cited 1 time

Online Publication Date: 6 June 2012

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We investigate the influence of polarity on carrier transport in single-quantum-well and multiple-quantum-well (MQW) light-emitting diodes (LEDs) grown on the semipolar (20math1) and (20math) orientations of free-standing GaN. For semipolar MQW LEDs with the opposite polarity to conventional Ga-polar c-plane LEDs, the polarization-related electric field in the QWs results in an additional energy barrier for carriers to escape the QWs. We show that semipolar (20math) MQW LEDs with the same polarity to Ga-polar c-plane LEDs have a more uniform carrier distribution and lower forward voltage than (20math1) MQW LEDs.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Sub-femtosecond absolute timing jitter with a 10 GHz hybrid photonic-microwave oscillator

T. M. Fortier, C. W. Nelson, A. Hati, F. Quinlan, J. Taylor, H. Jiang, C. W. Chou, T. Rosenband, N. Lemke, A. Ludlow, D. Howe, C. W. Oates, and S. A. Diddams

Appl. Phys. Lett. 100, 231111 (2012); http://dx.doi.org/10.1063/1.4726122 (3 pages) | Cited 3 times

Online Publication Date: 7 June 2012

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We present an optical-electronic approach to generating microwave signals with high spectral purity. By circumventing shot noise and operating near fundamental thermal limits, we demonstrate 10 GHz signals with an absolute timing jitter for a single hybrid oscillator of 420 attoseconds (1 Hz–5 GHz).
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84.40.-x Radiowave and microwave (including millimeter wave) technology
85.60.-q Optoelectronic devices
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

High temperature single photon emitter monolithically integrated on silicon

L. Cavigli, S. Bietti, N. Accanto, S. Minari, M. Abbarchi, G. Isella, C. Frigeri, A. Vinattieri, M. Gurioli, and S. Sanguinetti

Appl. Phys. Lett. 100, 231112 (2012); http://dx.doi.org/10.1063/1.4726189 (4 pages) | Cited 5 times

Online Publication Date: 7 June 2012

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We report on triggered single photon emission from GaAs quantum dots, grown on Si substrates and obtained by means of fabrication protocols compatible with the monolithic integration on Si based microelectronics. Very bright and sharp individual exciton lines are resolved in the spectra and can be followed up to 150 K. The nature of quantum emitters of single photon pulses can be measured up to liquid nitrogen temperature by Hanbury Brown and Twiss interferometric correlations.
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78.67.Hc Quantum dots
85.60.-q Optoelectronic devices
71.35.-y Excitons and related phenomena

GaN-based light-emitting diodes on origami substrates

Younghun Jung, Xiaotie Wang, Jiwan Kim, Sung Hyun Kim, Fan Ren, Stephen J. Pearton, and Jihyun Kim

Appl. Phys. Lett. 100, 231113 (2012); http://dx.doi.org/10.1063/1.4726123 (3 pages) | Cited 1 time

Online Publication Date: 8 June 2012

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GaN-based light-emitting diodes (LEDs) were transferred to paper substrates after a laser lift-off (LLO) process with an ArF excimer laser system (λ = 193 nm) to remove the sapphire substrate and produce freestanding blue LED templates. The threshold voltage (∼2.7 V), current-voltage characteristics, and peak emission wavelength (442 nm) were not changed after the paper substrate was subsequently wrinkled. We were able to demonstrate transfers to both planar and folded (origami) paper structures, showing the promise of the LLO process for transferring LEDs to arbitrary surfaces.
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85.60.Jb Light-emitting devices

Bandwidth enhancement and optical performances of multiple quantum well transistor lasers

Iman Taghavi, Hassan Kaatuzian, and Jean-Pierre Leburton

Appl. Phys. Lett. 100, 231114 (2012); http://dx.doi.org/10.1063/1.4727898 (5 pages) | Cited 1 time

Online Publication Date: 8 June 2012

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A detailed rate-equation-based model is developed to study carrier transport effects on optical and electrical characteristics of the multiple quantum well heterojunction bipolar transistor laser in time-domain. Simulation results extracted using numerical techniques in small-signal regime predict significant enhancement in device optical bandwidth when multiple quantum wells are used. Cavity length and base width are also modified to optimize the optoelectronic performances of the device. An optical bandwidth of ≈60 GHz is achieved in the case of 5 quantum wells each of 70 Å widths and a cavity length of 200 μm.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.30.Pq Bipolar transistors
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.60.-q Optoelectronic devices

Simultaneous determination of the constituent azimuthal and radial mode indices for light fields possessing orbital angular momentum

Michael Mazilu, Areti Mourka, Tom Vettenburg, Ewan M. Wright, and Kishan Dholakia

Appl. Phys. Lett. 100, 231115 (2012); http://dx.doi.org/10.1063/1.4728111 (4 pages) | Cited 1 time

Online Publication Date: 8 June 2012

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A wide array of diffractive structures such as arrays of pinholes, triangular apertures, slits, and holograms have all recently been used to measure the azimuthal index of individual Laguerre-Gaussian beams. Here, we demonstrate a powerful approach to simultaneously measure both the radial and azimuthal indices of pure Laguerre-Gaussian light fields using the method of principal component analysis. We find that the shape of the diffracting element used to measure the mode indices is in fact of little importance and the crucial step is training any diffracting optical system and transforming the observed pattern into uncorrelated variables. The method is generic and may be extended to other families of light fields such as Bessel or Hermite-Gaussian beams.
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07.60.-j Optical instruments and equipment
42.79.Dj Gratings
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Charge transfer effects in electrocatalytic Ni-C revealed by x-ray photoelectron spectroscopy

G. E. Haslam, K. Sato, T. Mizokawa, X.-Y. Chin, and G. T. Burstein

Appl. Phys. Lett. 100, 231601 (2012); http://dx.doi.org/10.1063/1.4722785 (3 pages) | Cited 1 time

Online Publication Date: 5 June 2012

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Binary Ni-C thin-film alloys, which have been shown to be passive against corrosion in hot sulphuric acid solution whilst also being electrocatalytically active, were investigated by XPS to determine the oxidation state of the metal and carbon components. The Ni component produces a Ni 2p spectrum similar to that of metallic nickel (i.e., no oxidation occurs) but with a 0.3 eV shift to higher binding energy (BE) due to electron donation to the carbon matrix. The C 1s peak shows a shift to lower BE by accepting electrons from the Ni nanocrystals. A cluster-model analysis of the observed Ni 2p spectrum is consistent with the electron transfer from the nickel to the carbon.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.65.Mq Oxidation
82.30.Fi Ion-molecule, ion-ion, and charge-transfer reactions

Enhanced oxidation of nanoscale In particles at the interface with a Si nanowire

E. Sutter and P. Sutter

Appl. Phys. Lett. 100, 231602 (2012); http://dx.doi.org/10.1063/1.4726054 (4 pages) | Cited 1 time

Online Publication Date: 6 June 2012

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We investigate the room-temperature oxidation of In nanoparticles at the tips of Si nanowires. This geometry allows a direct comparison of oxidation at the gas-indium interface and the interface to the Si nanowire. While the In2O3 at the free surface is polycrystalline with small limiting thickness, the oxidation at the nanoscale interface to Si gives rise to single crystalline In2O3 with a tenfold-enhanced thickness. Our results demonstrate interfacial modifications of oxidation at the nanoscale, which need to be considered in scaling electronic devices, and which can become a route for forming high-quality semiconductor-oxide interfaces in nanostructured materials, such as nanowires.
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81.65.Mq Oxidation

Oxygen migration process in the interfaces during bipolar resistance switching behavior of WO3−x-based nanoionics devices

Rui Yang, Kazuya Terabe, Tohru Tsuruoka, Tsuyoshi Hasegawa, and Masakazu Aono

Appl. Phys. Lett. 100, 231603 (2012); http://dx.doi.org/10.1063/1.4726084 (4 pages) | Cited 3 times

Online Publication Date: 6 June 2012

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Bipolar resistance switching (BRS) behavior and the effects of atmosphere (air, vacuum, O2 gas, or N2 gas) on BRS behavior occurred in the top and bottom interfaces in the M(top electrode)/WO3−x/Pt(bottom electrode) (M = Pt, Au) devices were investigated. Stable BRS only can be obtained in the interface with Pt electrode. And, the top Pt/WO3−x interface exhibited stable BRS only in an oxygen-rich atmosphere (air and O2 gas). In contrast, the bottom WO3−x/Pt interface showed stable BRS under any atmosphere. Based on the x-ray photoelectron spectroscopy measurement on Pt, Au/WO3−x interfaces, it is identified that the oxygen migration process during resistance switching mainly occurs between the Pt/WO3−x interface and Pt electrode.
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84.30.Sk Pulse and digital circuits
85.30.Pq Bipolar transistors
84.32.Dd Connectors, relays, and switches

Mechanism of non-metal catalytic growth of graphene on silicon

Guo Hong, Qi-Hui Wu, Jianguo Ren, and Shuit-Tong Lee

Appl. Phys. Lett. 100, 231604 (2012); http://dx.doi.org/10.1063/1.4726114 (5 pages) | Cited 2 times

Online Publication Date: 6 June 2012

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Compared to preparation on metal substrates, graphene synthesis on non-metal surfaces is highly desirable to avoid the deleterious metallic effects in fabrication of electronic devices. However, study of graphene growth mechanism on non-metal surfaces is rare and little understood. Here, we report that few-layers graphene films can be grown directly on silicon-on-insulator surface. Furthermore, the graphene growth mechanism on non-metal surfaces is proposed as a surface reaction, adsorption, decomposition, and accumulation process.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
64.75.Bc Solubility
81.05.ue Graphene
68.43.Mn Adsorption kinetics

Plasma plume effects on the conductivity of amorphous-LaAlO3/SrTiO3 interfaces grown by pulsed laser deposition in O2 and Ar

A. Sambri, D. V. Cristensen, F. Trier, Y. Z. Chen, S. Amoruso, N. Pryds, R. Bruzzese, and X. Wang

Appl. Phys. Lett. 100, 231605 (2012); http://dx.doi.org/10.1063/1.4727905 (4 pages) | Cited 2 times

Online Publication Date: 6 June 2012

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Amorphous-LaAlO3/SrTiO3 interfaces exhibit metallic conductivity similar to those found for the extensively studied crystalline-LaAlO3/SrTiO3 interfaces. Here, we investigate the conductivity of the amorphous-LaAlO3/SrTiO3 interfaces grown in different pressures of O2 and Ar background gases. During the deposition, the LaAlO3 ablation plume is also studied, in situ, by fast photography and space-resolved optical emission spectroscopy. An interesting correlation between interfacial conductivity and kinetic energy of the Al atoms in the plume is observed: to assure conducting interfaces of amorphous-LaAlO3/SrTiO3, the kinetic energy of Al should be higher than 1 eV. Our findings add further insights on mechanisms leading to interfacial conductivity in SrTiO3-based oxide heterostructures.
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73.40.-c Electronic transport in interface structures
52.77.Dq Plasma-based ion implantation and deposition
81.15.Fg Pulsed laser ablation deposition

Fast crystal nucleation induced by surface oxidation in Si-doped GeTe amorphous thin film

Yuta Saito, Yuji Sutou, and Junichi Koike

Appl. Phys. Lett. 100, 231606 (2012); http://dx.doi.org/10.1063/1.4726107 (4 pages) | Cited 2 times

Online Publication Date: 7 June 2012

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Fast crystallization in the phase change materials (PCMs) used for optical and electrical phase change memory improves their data recording rate. In the present work, it was found that the preferential surface oxidation of Si shortens the nucleation time of Ge46.55Te46.55Si6.9 amorphous films. The nucleation time of a surface-oxidized film was approximately 20% faster than that of a non-oxidized film. This was due to the formation of inhomogeneous nucleation sites at the film surface. These results suggest that preferential surface oxidation of PCM is an effective method to enhance the data recording rate of phase change memory devices.
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68.55.ag Semiconductors
81.05.Gc Amorphous semiconductors
81.65.Mq Oxidation

Laterally confined two-dimensional electron gases in self-patterned LaAlO3/SrTiO3 interfaces

M. Foerster, R. Bachelet, V. Laukhin, J. Fontcuberta, G. Herranz, and F. Sánchez

Appl. Phys. Lett. 100, 231607 (2012); http://dx.doi.org/10.1063/1.4728109 (5 pages) | Cited 1 time

Online Publication Date: 7 June 2012

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A bottom-up process has been used to engineer the LaAlO3/SrTiO3 interface atomic composition and locally confine the two-dimensional electron gas to lateral sizes in the order of 100 nm. This is achieved by using SrTiO3(001) substrate surfaces with self-patterned chemical termination, which is replicated by the LaAlO3 layer, resulting in a modulated LaO/TiO2 and AlO2/SrO interface composition. We demonstrate the confinement of the conducting interface forming either long-range ordered nanometric stripes or isolated regions. Our results demonstrate that engineering the interface chemical termination is a suitable strategy towards nanoscale lateral confinement of two-dimensional high-mobility systems.
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73.40.-c Electronic transport in interface structures
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.35.Ct Interface structure and roughness
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Micro-Brillouin spectroscopy mapping of the residual density field induced by Vickers indentation in a soda-lime silicate glass

H. Tran, S. Clément, R. Vialla, D. Vandembroucq, and B. Rufflé

Appl. Phys. Lett. 100, 231901 (2012); http://dx.doi.org/10.1063/1.4725488 (4 pages) | Cited 1 time

Online Publication Date: 4 June 2012

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High-resolution Brillouin scattering is used to achieve 3-dimensional maps of the longitudinal acoustic mode frequency shift in soda-lime silicate glasses subject to Vickers indentations. Assuming that residual stress-induced effects are simply proportional to density changes, residual densification fields are obtained. The density gradient is nearly isotropic, confirming earlier optical observations made on a similar glass. The results show that Brillouin micro-spectroscopy opens the way to a fully quantitative comparison of experimental data with predictions of mechanical models for the identification of a constitutive law.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
78.35.+c Brillouin and Rayleigh scattering; other light scattering
62.65.+k Acoustical properties of solids
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation

Shear instability of nanocrystalline silicon carbide during nanometric cutting

Saurav Goel, Xichun Luo, and Robert L. Reuben

Appl. Phys. Lett. 100, 231902 (2012); http://dx.doi.org/10.1063/1.4726036 (5 pages) | Cited 2 times

Online Publication Date: 4 June 2012

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The shear instability of the nanoscrystalline 3C-SiC during nanometric cutting at a cutting speed of 100 m/s has been investigated using molecular dynamics simulation. The deviatoric stress in the cutting zone was found to cause sp3-sp2 disorder resulting in the local formation of SiC-graphene and Herzfeld-Mott transitions of 3C-SiC at much lower transition pressures than that required under pure compression. Besides explaining the ductility of SiC at 1500 K, this is a promising phenomenon in general nanoscale engineering of SiC. It shows that modifying the tetrahedral bonding of 3C-SiC, which would otherwise require sophisticated pressure cells, can be achieved more easily by introducing non-hydrostatic stress conditions.
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81.40.Lm Deformation, plasticity, and creep
62.20.fk Ductility, malleability
64.70.kg Semiconductors
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
71.30.+h Metal-insulator transitions and other electronic transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

High thermoelectric performance of solid solutions CuGa1−xInxTe2 (x = 0–1.0)

Yapeng Li, Qingsen Meng, Yuan Deng, Hong Zhou, Yulan Gao, Yiyun Li, Jiangfeng Yang, and Jiaolin Cui

Appl. Phys. Lett. 100, 231903 (2012); http://dx.doi.org/10.1063/1.4726109 (4 pages) | Cited 3 times

Online Publication Date: 4 June 2012

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We synthesized the solid solutions CuGa1−xInxTe2 (x = 0–1.0) by isoelectronic substitution of element In (Ga) for Ga(In) in the CuMTe2 (M = Ga, In) lattices and examined their thermoelectric properties. The structure upon substitution provides much high Seebeck coefficient (α), relatively low thermal (κ), and electrical conductivity (σ). AT 701 K, the α, σ, and κ are 283.15 µV K−1, 1.15 × 104 Ω−1 m−1, and 0.71 W m−1 K−1, respectively, for CuGa0.36In0.64Te2, which give the figure of merit (ZT) of 0.91, about two times those of the mother compounds CuGaTe2 and CuInTe2. This material holds great application perspectives at intermediate temperatures.
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72.20.Pa Thermoelectric and thermomagnetic effects
61.66.-f Structure of specific crystalline solids
82.30.Hk Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)
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