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14 May 2012

Volume 100, Issue 20 (partial)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 203104 (2012); http://dx.doi.org/10.1063/1.3701731 (4 pages)

Z. Y. Jiang, X. X. Jiang, S. Su, X. P. Wei, S. T. Lee, and Y. He
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Near threshold all-optical backaction amplifier

Terry G. McRae and Warwick P. Bowen

Appl. Phys. Lett. 100, 201101 (2012); http://dx.doi.org/10.1063/1.4717717 (3 pages)

Online Publication Date: 14 May 2012

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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 achieved for only 12 μW of input power. Minor parameter adjustment allows narrowband optical filtering.
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42.55.Wd Fiber lasers
42.79.Ci Filters, zone plates, and polarizers

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, Da Wang, and Wei Zhang

Appl. Phys. Lett. 100, 201102 (2012); http://dx.doi.org/10.1063/1.4718353 (4 pages)

Online Publication Date: 14 May 2012

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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 coupling in PBG, low switching power of 9.2 mW and high extinction ratio of 17 dB are achieved experimentally while the length of DS-PCWG is only 16 μm.
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42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.70.Qs Photonic bandgap materials
42.79.Gn Optical waveguides and couplers

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

S. Jain, M. Sysak, M. Swaidan, and J. Bowers

Appl. Phys. Lett. 100, 201103 (2012); http://dx.doi.org/10.1063/1.4714725 (4 pages)

Online Publication Date: 14 May 2012

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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 × 10−7 Ω cm2 and < 2 × 10−6 Ω cm2 is obtained on n-InP and p-InGaAs after 450 °C anneal using circular transmission line model (CTLM) patterns. In addition, by varying the atomic ratio of Pd/Ge we, propose a common metal contact to both group III–V epitaxial layers with a specific contact resistivity <1 × 10−5 Ω cm2.
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42.82.-m Integrated optics
73.40.Cg Contact resistance, contact potential

Control of tensile strain in germanium waveguides through silicon nitride layers

A. Ghrib, M. de Kersauson, M. El Kurdi, R. Jakomin, G. Beaudoin, S. Sauvage, G. Fishman, G. Ndong, M. Chaigneau, R. Ossikovski, I. Sagnes, and P. Boucaud

Appl. Phys. Lett. 100, 201104 (2012); http://dx.doi.org/10.1063/1.4718525 (4 pages)

Online Publication Date: 15 May 2012

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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 Γ valley can also be significantly increased when the ridges are oriented along the 〈100〉 direction. We demonstrate an uniaxial strain transfer up to 1% observed on the room temperature direct band gap photoluminescence of germanium. The results are supported by 30 band k·p modeling of the electronic structure and the finite element modeling of the strain field.
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42.79.Gn Optical waveguides and couplers

Plasmons in electrostatically doped graphene

Sukosin Thongrattanasiri, Iván Silveiro, and F. Javier García de Abajo

Appl. Phys. Lett. 100, 201105 (2012); http://dx.doi.org/10.1063/1.4714688 (4 pages)

Online Publication Date: 15 May 2012

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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 nanostructured graphene. Specifically, we investigate backgated ribbons, co-planar ribbon pairs placed at opposite potentials, and individual ribbons subject to a uniform electric field. Plasmons in backgated ribbons and ribbon pairs are similar to those of uniformly doped ribbons, provided the Fermi energy is appropriately scaled to compensate for finite-size effects such as the divergence of the carrier density at the edges. In contrast, the plasmons of a ribbon exposed to a uniform field exhibit distinct dispersion and spatial profiles that considerably differ from uniformly doped ribbons. Our results provide a road map to understand graphene plasmons under realistic electrostatic doping conditions.
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73.22.Pr Electronic structure of graphene
71.20.Tx Fullerenes and related materials; intercalation compounds
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
72.80.Vp Electronic transport in graphene

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, Robert F. Davis, and Jonathan A. Malen

Appl. Phys. Lett. 100, 201106 (2012); http://dx.doi.org/10.1063/1.4718354 (4 pages)

Online Publication Date: 16 May 2012

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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 100 nm thick AlN layer has k = 0.93 ± 0.16 W/mK at 300 K, which is suppressed >100 times relative to bulk AlN. Transmission electron microscope images revealed high dislocation densities (4 × 1010 cm−2) within AlN and a severely defective AlN-SiC interface that cause additional phonon scattering. Resultant thermal resistances degrade LED performance and lifetime making layer-by-layer k, a critical design metric for LEDs.
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66.70.Df Metals, alloys, and semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
85.60.Jb Light-emitting devices
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Color control through plasmonic metal gratings

M. A. Vincenti, M. Grande, D. de Ceglia, T. Stomeo, V. Petruzzelli, M. De Vittorio, M. Scalora, and A. D’Orazio

Appl. Phys. Lett. 100, 201107 (2012); http://dx.doi.org/10.1063/1.4718764 (4 pages)

Online Publication Date: 16 May 2012

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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. Experimental proof of this shift is provided by the observation of an important change in the color of the diffracted field. Calculations of the diffracted spectra match the observed color changes very well and provide an efficient means for the design of sensing platforms based on color observation.
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78.66.Bz Metals and metallic alloys
73.22.Lp Collective excitations
42.79.Dj Gratings
71.20.Be Transition metals and alloys

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, Shinichi Tanaka, Chih-Chien Pan, Yoshinobu Kawaguchi, Kenji Fujito, Chris G. Van de Walle, James S. Speck, Steven P. DenBaars, Shuji Nakamura, and Daniel Feezell

Appl. Phys. Lett. 100, 201108 (2012); http://dx.doi.org/10.1063/1.4719100 (4 pages)

Online Publication Date: 16 May 2012

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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 (20mathmath) and (11math2) planes have the highest indium incorporation rate among the studied planes. We also show that both indium composition and polarization-related electric fields impact the emission wavelength of the quantum wells (QWs). The different magnitudes and directions of the polarization-related electric fields for each orientation result in different potential profiles for the various semipolar and nonpolar QWs, leading to different emission wavelengths at a given indium composition.
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78.60.Fi Electroluminescence
78.67.De Quantum wells

Taming the thermal emissivity of metals: A metamaterial approach

N. Mattiucci, G. D’Aguanno, A. Alù, C. Argyropoulos, J. V. Foreman, and M. J. Bloemer

Appl. Phys. Lett. 100, 201109 (2012); http://dx.doi.org/10.1063/1.4719582 (4 pages)

Online Publication Date: 16 May 2012

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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 guided mode resonances along the grating, nor on the absorption resonances of extremely shallow metallic grating. Instead, we exploit the effective bulk properties of a thick metallic grating below the first diffraction order. We analytically model this physical mechanism of temporally coherent thermal emission based on localized bulk resonances in the grating. We validate our theoretical predictions with full-wave numerical simulations.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.79.Dj Gratings
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
78.20.N- Thermo-optic effects
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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, J. K. Schoelz, T. B. Bothwell, Salvador Barraza-Lopez, L. Bellaiche, and P. M. Thibado

Appl. Phys. Lett. 100, 201601 (2012); http://dx.doi.org/10.1063/1.4716475 (4 pages)

Online Publication Date: 14 May 2012

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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-energy barrier direction of the top layer displacement is toward a structure where none of the carbon pz orbitals overlap, while the high-energy barrier direction is toward AA stacking. Each directional shift yields a real-space surface charge density similar to graphene; however, the low-energy barrier direction requires only one bond length to convert ABA (Bernal) to ABC (rhombohedral).
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
61.48.Gh Structure of graphene

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

C. X. Zheng, W. X. Tang, and D. E. Jesson

Appl. Phys. Lett. 100, 201602 (2012); http://dx.doi.org/10.1063/1.4718305 (4 pages)

Online Publication Date: 15 May 2012

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The displacive adsorption of As on 1 × 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 tensile surface stress associated with 1 × 1 As:Si(111). Cycling the incident As flux on and off creates surface roughening via respective displacive adsorption and evaporation of As. This roughness facilitates increased 1 × 1 As:Si(111) coverage during As deposition due to surface stress relief at steps.
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68.35.Gy Mechanical properties; surface strains
68.43.Fg Adsorbate structure (binding sites, geometry)
68.47.Fg Semiconductor surfaces
61.72.uf Ge and Si
68.35.bg Semiconductors
68.35.Dv Composition, segregation; defects and impurities

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, S. Spadoni, L. Avaro, A. Liscio, V. Palermo, and L. Ottaviano

Appl. Phys. Lett. 100, 201603 (2012); http://dx.doi.org/10.1063/1.4714774 (4 pages)

Online Publication Date: 15 May 2012

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SiO2 and Al2O3 surfaces exposed to periodically modulated extreme ultraviolet (EUV) light (λ = 46.9 nm) have been investigated at the μm scale by optical microscopy, scanning electron microscopy, scanning Auger microscopy, atomic force microscopy, and Kelvin probe force microscopy. The formation of a carbon contamination layer preserving the same periodical modulation of the EUV dose has been observed. The mechanisms of hydrocarbon molecules deposition have been studied with the help of correlation plots between the modulated Auger signal and the corresponding EUV dose. A surface-dependent secondary-electron-based model has been proposed.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Ms Insulators
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Ps Atomic force microscopy (AFM)
81.65.-b Surface treatments

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

Appl. Phys. Lett. 100, 201604 (2012); http://dx.doi.org/10.1063/1.4717465 (5 pages)

Online Publication Date: 15 May 2012

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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 films after drying. Pre-functionalization of the textured surfaces with anionic surfactants prevents particle coagulation during contact charging and decreases sheet resistance to metal-like levels (∼60 Ω/□). Conductivity of the films can be tuned by controlling the rate of acid evaporation. Conductive films are highly stable under ambient conditions and show no hysteresis when biased with zero delay-time.
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82.35.Gh Polymers on surfaces; adhesion
68.55.jm Texture
61.41.+e Polymers, elastomers, and plastics
68.08.Bc Wetting
73.40.Cg Contact resistance, contact potential
73.61.Ph Polymers; organic compounds

Interfacial interaction of gas molecules and single-walled carbon nanotubes

Jun Zhong, Jauwern Chiou, Chungli Dong, Per-Anders Glans, Way-Faung Pong, Chinglin Chang, Ziyu Wu, and Jinghua Guo

Appl. Phys. Lett. 100, 201605 (2012); http://dx.doi.org/10.1063/1.4718421 (4 pages)

Online Publication Date: 16 May 2012

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The interfacial interaction between single-walled carbon nanotubes (SWNTs) and various gas molecules (H2, He, and N2) 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 interaction (involving external and internal collisions) between SWNTs and various gas molecules under different pressures. At gas pressures higher than 5 Torr, the unoccupied states of SWNTs show some features corresponding to the structure deformation with a reversible behavior when cycling under vacuum and gas conditions. The XANES study for different gases (H2, He, and N2) shows a strong dependence of gas molecular weight, which provides experimental evidence to the gas scattering mechanism.
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78.70.Dm X-ray absorption spectra
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
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On the characteristic length scales associated with plastic deformation in metallic glasses

P. Murali, Y. W. Zhang, and H. J. Gao

Appl. Phys. Lett. 100, 201901 (2012); http://dx.doi.org/10.1063/1.4717744 (4 pages)

Online Publication Date: 14 May 2012

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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 ℓc that governs Poisson’s ratio ν, shear band thickness tSB, and fracture mode in these materials. Among the three glasses, FeP exhibits smallest ℓc, thinnest tSB, lowest ν, and brittle fracture; CuZr exhibits largest ℓc, thickest tSB, highest ν, and ductile fracture, while properties of MgAl lie in between those of FeP and CuZr. These findings corroborate well with existing experimental observations and suggest ℓc as a fundamental measure of the shear transformation zone size in metallic glasses.
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81.05.Kf Glasses (including metallic glasses)
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Lm Deformation, plasticity, and creep
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.fq Plasticity and superplasticity
81.05.Bx Metals, semimetals, and alloys

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

Jun Lin and Megan T. Valentine

Appl. Phys. Lett. 100, 201902 (2012); http://dx.doi.org/10.1063/1.4717988 (4 pages)

Online Publication Date: 14 May 2012

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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 both push and pull on microscale magnetic beads, opening new avenues for the micromanipulation of soft materials. We demonstrate the application of such a device to oscillatory microrheology measurements of soft networks of microtubules, an essential cellular biopolymer.
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85.70.Ay Magnetic device characterization, design, and modeling
87.17.-d Cell processes

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

Chengying Tang (唐成颖), Yun-Mo Sung, and Joonho Lee

Appl. Phys. Lett. 100, 201903 (2012); http://dx.doi.org/10.1063/1.4712599 (3 pages)

Online Publication Date: 14 May 2012

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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. We report the size-dependence of the melting temperature (Tm) of Ag NPs by both differential scanning calorimetry experiments and thermodynamic assessments. Thermodynamically calculated Tm for the Ag NPs showed a nonlinear function with respect to the inverse of the particle size and agreed well with the present and reported experimental results within an error of 1 K.
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64.70.Nd Structural transitions in nanoscale materials
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)

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

T. Angelova, N. Shtinkov, Ts. Ivanov, V. Donchev, A. Cantarero, Ch. Deneke, O. G. Schmidt, and A. Cros

Appl. Phys. Lett. 100, 201904 (2012); http://dx.doi.org/10.1063/1.4714542 (4 pages)

Online Publication Date: 14 May 2012

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Rolled-up semiconductor tubes of various diameters made of alternating In0.215Ga0.785As/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 formation, the frequency of the phonon modes shifts with respect to the as-grown material and disorder activated modes are observed. The frequency shifts are related to the residual strain in the tubes through the deformation potential approximation. Good agreement with atomistic valence force field simulations and x-ray micro-diffraction measurements is found. By comparison with x-ray data, a Raman strain constant K = 0.65 is proposed for In0.215Ga0.785As. In the low frequency range, acoustic mode doublets are observed on the tubes that are absent in the surrounding material. They show clear evidence of the formation of periodic superlattices after the rolling-up process, and give insight into the quality of their interfaces.
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78.66.Fd III-V semiconductors
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
68.65.Cd Superlattices
78.30.-j Infrared and Raman spectra
78.30.Fs III-V and II-VI semiconductors

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

Appl. Phys. Lett. 100, 201905 (2012); http://dx.doi.org/10.1063/1.4718524 (4 pages)

Online Publication Date: 15 May 2012

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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 frequency is observed to be 0.4 THz which corresponds to a wavelength of 12.5 nm, the periodicity of the multiple quantum wells, and the estimated phonon velocity corresponds to the transverse acoustic phonon velocity in GaN. Moreover, we can magnify the driving amplitude of the generated shear phonons by increasing the reverse bias of the p-i-n diode.
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85.30.Kk Junction diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Anomalous phase change characteristics in Fe-Te materials

X. T. Fu, W. D. Song, H. W. Ho, R. Ji, L. Wang, and M. H. Hong

Appl. Phys. Lett. 100, 201906 (2012); http://dx.doi.org/10.1063/1.4719074 (4 pages)

Online Publication Date: 16 May 2012

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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 °C for Fe1.19Te and can be adjusted by the Fe/Te ratio. High-speed phase change in the Fe-Te materials has been demonstrated by nanosecond laser irradiation. Comparing to conventional phase change materials, the Fe-Te materials exhibit an anomalous optical property that has higher reflectivity at amorphous than crystalline state, which is useful for data storage design.
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61.43.-j Disordered solids
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.40.Kc Metals, semimetals, and alloys
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Partially filled intermediate band of Cr-doped GaN films

S. Sonoda

Appl. Phys. Lett. 100, 202101 (2012); http://dx.doi.org/10.1063/1.4717716 (4 pages)

Online Publication Date: 14 May 2012

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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 the material move in the inserted band. Prototype solar cells showed enhanced short circuit current and open circuit voltage in the n-GaN/GaCrN/p-GaN structure compared to the GaCrN/p-GaN structure, which validates the proposed concept of an intermediate-band solar cell.
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81.05.Ea III-V semiconductors
81.15.Cd Deposition by sputtering
88.40.jm Thin film III-V and II-VI based solar cells
71.20.Nr Semiconductor compounds
78.66.Fd III-V semiconductors
79.60.Dp Adsorbed layers and thin films

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, Nancy M. Haegel, Eugene E. Haller, Guido Ciampi, Hadong Kim, and Kanai S. Shah

Appl. Phys. Lett. 100, 202102 (2012); http://dx.doi.org/10.1063/1.4712596 (4 pages)

Online Publication Date: 14 May 2012

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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 energies of 0.11, 0.45, and 0.75 eV. CL measurements in both materials correlate with optical transitions involving some of the identified levels. The ambipolar carrier lifetimes of Se-doped and Pb-doped TlBr were measured with microwave reflectivity transients and found to be significantly lower than the lifetime of undoped TlBr.
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71.55.Ht Other nonmetals
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.60.Hk Cathodoluminescence, ionoluminescence
71.20.Nr Semiconductor compounds

Trace analysis of non-basal plane misfit stress relaxation in (20math1) and (30mathmath) semipolar InGaN/GaN heterostructures

Matthew T. Hardy, Po Shan Hsu, Feng Wu, Ingrid L. Koslow, Erin C. Young, Shuji Nakamura, Alexey E. Romanov, Steven P. DenBaars, and James S. Speck

Appl. Phys. Lett. 100, 202103 (2012); http://dx.doi.org/10.1063/1.4716465 (4 pages)

Online Publication Date: 14 May 2012

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We have studied primary and secondary slip systems in the relaxation of lattice mismatch stresses in (20math1) and (30mathmath) semipolar InxGa1−xN/GaN heterostructures by analyzing the geometry of traces associated with dislocations employing cathodoluminescence, x-ray diffraction, and transmission electron microscopy. For (20math1) InxGa1−xN/GaN heterostructures, the primary relaxation is by dislocation glide on the c-plane 11math0(0001) slip system and secondary relaxation is by dislocation glide on inclined planes including the m-plane 〈11math0〉{1math00} slip system. For (30mathmath) grown heterostructures non-basal slip, namely dislocation glide on the m-plane slip system, is the initial stress relaxation pathway.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
68.35.Ct Interface structure and roughness
78.60.Hk Cathodoluminescence, ionoluminescence

Charge instability of atomic-layer deposited TaSiOx insulators on Si, InP, and In0.53Ga0.47As

V. V. Afanas’ev, H.-Y. Chou, N. H. Thoan, C. Adelmann, H. C. Lin, M. Houssa, and A. Stesmans

Appl. Phys. Lett. 100, 202104 (2012); http://dx.doi.org/10.1063/1.4710553 (4 pages)

Online Publication Date: 15 May 2012

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Low barriers for electrons are found to be the reason for significant charge instability at interfaces of (100)InP and (100)In0.53Ga0.47As with atomic-layer deposited TaSiOx insulators. The formation of these reduced barriers is associated with the growth of a narrow-bandgap interlayer between the semiconductor and TaSiOx, which enables electron tunneling at low electric fields and subsequent trapping in the insulator. A wide-gap passivation layer may be required to improve the performance of TaSiOx as gate insulator.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Dynamics of localized excitons in Ga0.69In0.31N0.015As0.985/GaAs quantum well: Experimental studies and Monte-Carlo simulations

M. Baranowski, R. Kudrawiec, M. Latkowska, M. Syperek, J. Misiewicz, and J. A. Gupta

Appl. Phys. Lett. 100, 202105 (2012); http://dx.doi.org/10.1063/1.4714739 (5 pages)

Online Publication Date: 15 May 2012

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Show Abstract
Time resolved photoluminescence (PL) spectroscopy has been applied to study dynamics of localized excitons in a single Ga0.7In0.3N0.015As0.985/GaAs quantum well (QW). The decay time constant, τPL, has been determined for different PL peak energies at various temperatures. An increase in temperature produced two effects: (i) a reduction of τPL and (ii) changes in the τPL dispersion. These two experimental observations as well as the shape of PL decay curves were very well reproduced by Monte-Carlo simulations of hopping excitons with parameters derived from PL and photoreflectance measurements for this QW.
Show PACS
78.67.De Quantum wells
78.47.J- Ultrafast spectroscopy (<1 psec)
78.47.D- Time resolved spectroscopy (>1 psec)
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors
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