bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waterproof coating on nonlinear optical crystal surfaces by photo–oxidation of silicone oil
Authors: Sato Nobuhiro , Sato Yuji , Okamoto Yoshiaki , Murahara Masataka 
Published: April 2011

ABSTRACTOrganic silicone oil was photo–chemically oxidized to change into SiO2 by using a ultraviolet (UV) excimer lamp, which developed an over–coating for a nonlinear optical crystal.In general, nonlinear optical crystals are used as a wavelength conversion element for laser. The crystals are, however, deliquescent and absorb moisture in the air, which causes clouding. They need heating in the oven to prevent it. It is desired to develop a protective film on the nonlinear optical crystals so as to be waterproof and transmit UV rays. We have, then, developed the waterproof and protective film on a KH2PO4 (KDP) surface, which was photo–chemically oxidized by using a silicone oil and Xe2 excimer lamp. The silicone oil was spin–coated on the KDP crystal surface, and then the Xe2 excimer lamp was vertically irradiated to the crystal surface. The O atoms in the air were photo–excited with the UV photon to generate high active O atoms. At the same time, the C—H and the Si—C bonds of the silicone oil were photo–dissociated because the photon energy of the UV photon is higher than the bonding energies of the C—H and Si—C. The siloxane of the silicone oil was consequently linked with the O2 that had been absorbed on the crystal surface to form SiOn. As a result, the SiO2 film was formed on the KDP crystal surface by the photo–oxidation of silicone oil.The infrared spectroscopy analysis (ATR-FTIR) was carried out to investigate the modified film. The results showed that as the time of lamp irradiation extended, the absorption peak of the —CH3 groups at 2900 cm−1 decreased, but the absorption peak of the —SiO groups at 1050cm−1 increased. At the lamp irradiation time of 90 minutes, the UV transmittance of the treated silicone oil improved to 88.9 % at the 260 nm, which is the wavelength of the fourth harmonic generation, while that of the untreated silicone oil was 56 %.The treated and untreated KDP crystals were tested for their waterproofing. The untreated crystal was completely dissolved thirty minutes after soaking in the water, and on the contrary, the KDP crystal with the film coating has neither been dissolved nor gotten cloudy for three months when soaking in water.
Micro-Raman Evaluation of Polycrystalline Silicon MEMS Devices
Authors: Serrano Justin R. , Phinney Leslie M. , Kearney Sean P. 
Published: April 2011

ABSTRACTMicro-Raman spectroscopy is a valuable tool for thermometry of operational polysilicon MEMS devices. By using the temperature-calibrated response of the optical phonon peak of the polysilicon Raman signature and the micron-scale spatial resolution achieved with a 488 nm Ar+ laser Raman probe, we have obtained spatially resolved steady-state thermal profiles of Joule-heated thermal flexure actuators. The measured thermal profiles are further compared to one-dimensional numerical models of the thermal response of the electrically heated devices.
Role of Fe and Ni Nanoparticles on Mechanical Properties of Alumina Thin Films deposited by Laser Ablation
Authors: Yarmolenko Sergey , Neralla Sudheer , Kumar Dhananjay , Sankar Jag , Liu Fude , Duscher Gerd 
Published: April 2011

AbstractThis paper reports our recent work on the improved mechanical properties of alumina thin films with embedded Fe and Ni nanoparticle layers. The Fe/Ni nanoparticles-alumina composite thin films have been deposited using a multi-target pulsed laser ablation technique. Every film consists of 10 layers of alumina and 9 intermediate layers of Fe or Ni nanoparticles. Alumina layer thickness kept constant (∼22 nm) and total thickness of multilayered films was in range 220-280 nm depending on metal deposition time. Composite thin films were deposited at six different substrate temperatures in the range 200-800°C. The mechanical properties measurements, performed by nanoindentation in continuous stiffness mode and applying Nix-Bhattacharya (hardness H) and King's model (Young's modulus E) for film-only properties, have shown that pure alumina films deposited at temperatures 200-500°C are relatively soft (H = 15 GPa, E = 190 GPa), while films deposited at ≥600°C are significantly harder (H = 32 GPa, E = 320 GPa). Grazing incidence XRD (GIXRD) data indicated that γ-alumina peaks exist in high temperature samples while alumina films deposited at ≥500°C were amorphous. Embedding Ni and Fe nanoparticle layers at 500°C led to significant increase of H and E (31 GPa and 365 GPa with Fe and 33 GPa and 380 GPa with Ni) and appearance of γ-alumina peaks in GIXRD. Embedding on metal nanoparticle layers does not change mechanical properties of alumina films deposited at 200°C, and significant hardening of metal containing films starts at 400°C. These results suggest that metal nanoparticles have a catalytic effect on the growth of alumina thin films with enhanced crystallinty. The effect of Ni and Fe nanoparticle size on mechanical properties of thin films has been studied times at substrate temperature 500°C using eight different metal deposition. HRTEM data have shown that metal nanopartiles have uniform particle size distribution and inter-particle separation in the layer. Size of Ni and Fe nanoparticles with highest effect on mechanical properties was 4 -6 nm.
3.3 μm high brightness LEDs
Authors: Matveev Boris A. , Zotova Nonna V. , Il'inskaya Natalya , Karandashev Sergey A. , Remennyi Maxim A. , Stus' Nicolay M. , Kovchavtsev Anatoly P. , Kuryshev Georgii L. , Polovinkin Vladimir G. , Tarakanova Natalya 
Published: April 2011

ABSTRACTDeep mesa etching and surface roughening have been implemented to InAs flip-chip LEDs emitting at 3300 nm (300 K). Near field and power measurements confirmed the output power enhancement of about 2 and brightness increase with and equivalent to a black body temperature of about 1250 K.
Investigation of Surface Passivation in InAs/GaSb Strained-Layer-Superlattices Using Picosecond Excitation Correlation Measurement and Variable-Area Diode Array Surface Recombination Velocity Measurement
Authors: Zhu Zhimei , Plis Elena , Amtout Abdenour , Bhattacharya Pallab , Krishna Sanjay 
Published: April 2011

ABSTRACTThe effect of ammonium sulfide passivation on InAs/GaSb superlattice infrared detectors was investigated using two complementary techniques, namely, picosecond excitation correlation (PEC) measurement and variable-area diode array (VADA) surface recombination velocity (SRV) measurement. PEC measurements were conducted on etched InAs/GaSb superlattice mesas, which were passivated in aqueous ammonium sulfide solutions of various strengths for several durations. The PEC signal's decay time constant (DTC) is proportional to carrier lifetimes. At 77 K the PEC signal's DTC of the as-grown InAs/GaSb superlattice sample was 2.0 ns, while that of the unpassivated etched sample was reduced to 1.2 ns by the surface states at the mesa sidewalls. The most effective ammonium sulfide passivation process increased the PEC signal's DTC to 10.4 ns. However it is difficult to isolate surface recombination from other processes that contribute to the lifetime using the PEC data, therefore a VADA SRV measurement was undertaken to determine the effect of passivation on surface recombination. The obtained SRV in the depletion region of the InAs/GaSb superlattice and GaSb junction was 1.1×106 cm/s for the unpassivated sample and 4.6×105 cm/s for the passivated sample. At 77 K the highest R0A value measured in our passivated devices was 2540 W cm2 versus 0.22 W cm2 for the unpassivated diodes. The results of the lifetime, the SRV and the R0A measurements indicate that ammonium sulfide passivation will improve the performance of InAs/GaSb superlattice infrared detectors.
On the nucleation of GaP/GaAs and the effect of buried stress fields
Authors: Zelcovit João Guilherme , Bortoleto José Roberto R. , Bettini Jefferson , Cotta Mônica 
Published: April 2011

ABSTRACTWe have recently shown that spatial ordering for epitaxially grown InP dots can be obtained using the periodic stress field of compositional modulation on the InGaP buffer layer. The aim of this present work is to study the growth of films of GaP by Chemical Beam Epitaxy (CBE), with in-situ monitoring by Reflection High Energy Electron Diffraction (RHEED), on layers of unstressed and stressed GaAs. Complementary, we have studied the role of a buried InP dot array on GaP nucleation in order to obtain three-dimensional structures. In both cases, the topographical characteristics of the samples were investigated by Atomic Force Microscopy (AFM) in non-contact mode. Thus vertically-coupled quantum dots of different materials have been obtained keeping the in-place spatial ordering originated from the composition modulation.
Growth of GaAs on (100) Ge and Vicinal Ge Surface by Migration Enhanced Epitaxy
Authors: Tanoto Hendrix , Yoon Soon Fatt , Loke Wan Khai , Fitzgerald Eugene A. , Dohrman Carl , Narayanan Balasubramanian , Tung Chih Hang 
Published: April 2011

ABSTRACTIn this paper, we present GaAs/Ge heteroepitaxy grown by RIBER32 solid-source Molecular Beam Epitaxy (SSMBE) with initial GaAs nucleation by migration-enhanced epitaxy (MEE) technique. We look at the influence of substrate temperature during the MEE and the influence of Ge surface orientation to the quality of the GaAs layer. Three samples were grown for this study; the first two samples, sample A and B, have surface orientation of (100) 6° offcut towards (111) plane. This surface orientation was chosen as to achieve double-atomic steps surface that is crucial to suppress anti-phase domain (APD) formation. These samples were then subjected to different temperature during the MEE process, 450°C for sample A and 250°C for sample B. The third sample, sample C, has the same MEE substrate temperature as sample A, which is 450°C but with nominal (100) surface orientation. The growth conditions and structure of the layers after the MEE process were kept constant across the three samples.We examine the structures and the optical quality of the samples by cross-sectional Transmission Electron Microscope (XTEM) and 5K photoluminescence (PL). Analyzing the XTEM images of sample A and B, it is found that the APD still appear in sample A while it is suppressed totally in sample B. It is also observed from sample A XTEM image that two APDs propagating with 45° and 135° angle, as measured from the GaAs/Ge interface, could meet with each other at certain layer thickness leading to self-annihilation. However, some of the self-annihilations took place only after the APDs propagated hundreds of nanometers in the GaAs layer, producing large undulation in the layer. As for sample B, we believe that the APD suppression is mainly due to the much lower nucleation temperature. At such low temperature, As dimers are adsorbed onto the substrate surface more readily with negligible re-evaporation. This ensures complete As coverage on the double-atomic steps Ge surface and minimize As vacancies that may act as defect initiation centers. Furthermore, the low substrate temperature shortens the migration distance of Ga adatoms, minimizing their adsorption into the kinks and step edges, resulting in two-dimensional growth mode instead of step-flow growth mode.Meanwhile, XTEM image of sample C shows APDs that propagated almost perpendicularly to the GaAs/Ge interface, making it unlikely for the self-annihilation mechanism to take event. It is understood that the direction of propagation of the APD relies on the atomic steps reconstruction of the Ge starting surface. In the case of single atomic-step surface, the APDs propagate almost perpendicularly to the interface. Finally, the 5K PL spectra of the embedded InGaAs single quantum-well in all the samples clearly demonstrate that the best optical quality comes from sample B; which we believe mainly because of the total suppression of APD, leading to much improved layer quality.
Evaluation on Defects of Er and Yb Implanted Al070Ga030As by Using Positron Annihilation Spectroscopy
Authors: Arai Tomoyuki , Uekusa Shin-ichiro , Uedono Akira 
Published: April 2011

ABSTRACTThe influence on defects of Er implanted Al0.70Ga0.30As was studied, using standard Positron Annihilation Spectroscopy (PAS) and Photoluminescence (PL) technique. The incident energy of mono-energetic positrons was implanted from 0.1 eV to 30 keV. The characterization of un-doped Al0.70Ga0.30As and Al0.70Ga0.30As:Er,Yb as implanted, and Al0.70Ga0.30As:Er,Yb annealed ranging from 500 to 900 °C were successfully studied by using PAS technique. Into the incident energy around 5keV, the shape parameter of Al0.70Ga0.30As:Er,Yb annealed ranging from 500 to 900 °C was decreased and the PL intensity also increased in response to the annealing temperature ranging from 500 to 900 °C.
Prediction of Young's Moduli of Low Dielectric Constant Materials by Atomistic Molecular Dynamics Simulation
Authors: Choi Hyuk Soon , Lee Taebum , Lee Hyosug , Kim Jongseob , Hong Ki-Ha , Kim Kwang Hee , Shin Jaikwang , Shin Hyun Jin , Jung Hyeon Dam , Choi Seung Hoon 
Published: April 2011

ABSTRACTThe interests of low-k dielectric materials to reduce capacitance in multilevel metal interconnects of integrated circuits are well known in the semiconductor industry. Mechanical properties of low-k film are currently the main issues. Improved hardness and modulus are desirable because, when building a multilayered stack and doing sequential processing, films go through chemical mechanical planarization. In this proceeding, we reports the Young's moduli of the typical low k materials, and the effects of various factors for Young's moduli of materials, such as, structures of precursors, density, and porosity. Using atomistic molecular dynamics simulation with experimental measurements, the Young's moduli of films of amorphous silicon oxide in which 25% of Si-O-Si chains were replaced by Si-(CH3 H3C)-Si, Si-CH2-Si, Si-(CH2)2-Si, Si-(CH2)3-Si, Si-(CH2)4-Si, Si-(CH2)6-Si, were measured and analyzed. The predicted trends of Young's moduli of films formed by above precursors are in good consistent with those observed from experiments. The Young's moduli of materials are largely dependent on the densities of materials. Young's modulus of material increases as the density of the material increases. The chemical properties, chain length, and connectivity of material take effects on the Young's modulus of material. Given the same densities of material the smaller number of cavities per unit volume the material has, the lower Young's modulus it shows. Based on the results, the method of predict mechanical properties of materials by the conjunction of basic experimental measurements and atomistic simulation will be discussed.
Thermal stability of nickel-cobalt multilayer silicide
Authors: Han Kil Jin , Cho Yu Jung , Oh Soon Young , Kim Yong Jin , Lee Won Jae , Lee Hi Deok , Kim Yeong-Cheol 
Published: April 2011

ABSTRACTIn this study, we have investigated the structure of nickel-cobalt silicide to understand its behavior at high temperature. Nickel-cobalt silicide was formed after two-step RTP at 500°C and 700°C respectively. We could observe by TEM that nickel-cobalt silicide consists of a structure which seems to be a Ni-Co-Si ternary phase. No nickel silicide phases and cobalt silicide phases were detected in nickel-cobalt silicide by XRD. From XPS depth profile, we could confirm that there is a cobalt composition gradient along the silicide.
Role Of Active Oxygen Species On Growth Of ZnO Using RF-PAMBE
Authors: Durbin Steven M. , Lee William C. T. , Allen Martin , Miller Paul , Reeves Roger J. 
Published: April 2011

ABSTRACTThe effect of different oxygen species on the RF plasma-assisted molecular beam epitaxy growth of ZnO films has been investigated. By varying the geometry of the aperture plate and also the RF power, the relative atomic content in the discharge was altered, and this is found to be corre-lated to the film quality. Further, growth rate studies performed in tandem with in-situ laser interferometry suggest that stoichiometric conditions may not result in saturation of growth rates.
ZnO Light-Emission Array Fabricated into Nanometer-scale Pits on Silicon Substrate
Authors: Ohashi Naoki , Sakaguchi Isao , Sekiguchi Takashi , Haneda Hajime , Kobayashi Kazuyoshi , Masauda Hidetoshi , Chazono Hirokazu , Fujimoto Masayuki 
Published: April 2011

ABSTRACTA nanometer-scale ZnO light emission array device was fabricated using the multi-level metallization technique of the CMOS process. Square arrays of pits with an inverted pyramid shape made from {111}Si planes were formed on a (100)Si substrate using selective etching. ZnO was deposited on the substrate by chemical vapor deposition (CVD), and the surface of the deposited ZnO film was carefully polished by chemical mechanical planarization (CMP). As a result, ZnO-filled nanometer-scale arrays were obtained after removing the ZnO layer except for the ZnO in the pits by CMP. Cathodoluminescence (CL) from the ZnO arrays was observed.
Optical Properties of Zinc Oxide Quantum Dots Embedded Films by Metal Organic Chemical Vapor Deposition
Authors: Tan S. T. , Sun X. W. , Zhang X. H. , Chen B. J. , Chua S. J. 
Published: April 2011

ABSTRACTZinc oxide (ZnO) quantum dots (QDs) embedded films were fabricated on silicon substrates by metal organic chemical vapor deposition at 350°C. The QDs can be obtained in a matrix of amorphous ZnO films by introducing a large amount of precursors. The size of the QDs ranged from 3 to 12 nm, which was estimated by high-resolution transmission electron microscopy. The photoluminescence measured at 80 K showed that the emission of QDs embedded film ranged from 3.0 to 3.6 eV. The broad near-band-edge emission is due to the quantum confinement effect of the QDs. The quantum confinement effect of the QDs disappears after the post-growth annealing due to the ripening of QDs.
Structural Studies of ZnO Calcined with Transition Metal Oxides
Authors: Noice Lori , Seipel Bjoern , Grathoff Georg , Gupta Amita , Moeck Peter , Rao V. K. 
Published: April 2011

ABSTRACTPowder X-ray diffraction analyses of Mn-and Cu-doped ZnO powders calcined at 500˚C, show shifts in the wurtzite type semiconductor's lattice constants and unit cell volume which correspond to the nominal concentrations of transition metal dopants. Marked reductions in the a-lattice constant and unit cell volume for a small concentration of Cu dopants, which is not maintained upon increased Cu concentration, suggest a change in the copper ion hybridization state due to the dopant concentration. In all the samples, only ZnO and CuO phases were detected, aiding the ascertainment of any ferromagnetic response from the samples as arising from the formation of a true dilute magnetic semiconductor.
Roles of Laser-Ablation of Mn in Initial Stage of Growth of ZnO Nanorods by Chemical Vapor Deposition
Authors: Hirate Takashi , Miyashita Hiroshi , Kimpara Takashi , Takizawa Kazumoto , Satoh Tomomasa 
Published: April 2011

ABSTRACTWe studied on effects of laser ablation on morphology of ZnO nanorods fabricated by low-pressure thermal chemical vapor deposition combined with laser ablation of Mn. In this paper, we studied on the effects of laser-ablation time period and energy density of laser beam at an initial stage of growth of ZnO nanorods. Both of laser ablation and chemical vapor deposition are started simultaneously and the laser ablation is stopped on the way of growth of ZnO nanorods. After the laser ablation is stopped, only chemical vapor deposition is continued. It is concluded from the experimental results that even if laser-ablation time period is only 30 sec and energy density of laser is only 0.023 Joule/cm2/pulse, the laser ablation shows remarkable effects on growth of ZnO nanorods.
Composition modulation and local structure in strained diluted GaInNAs nitride alloy thin layers on GaAs substrates
Authors: Metsue Arnaud , Priester Catherine 
Published: April 2011

ABSTRACTThe theoretical study reported here is devoted to diluted GaInNAs nitride alloys, and focuses on correlation between local chemical atomic neighborhood and atomic distances. The model used is Valence Force Field approximation, and we model a periodic Ga1−xInxNyAs1−y alloy film deposited on a GaAs substrate. The surface is dimerised (for simplicity we consider 2×1 anion rich surfaces). First starting from a random film, first and second nearest neighbor distances are calculated, and the corresponding histogram drawn. Then a pseudo-annealing process is simulated by allowing the N atoms to choose their optimal location. This pseudo-annealing strongly enhances the number of In-N bonds, in agreement to experimental studies. From this statistical study, fine structure of each peak of the histograms is shown to be not directly related to a given surrounding chemical distribution up to 3rd nearest neighbors. The positions (in distance) of the peaks appear not to be modified by alloy composition nor alloy segregation, which only alter relative intensities and peak shapes. Last, we consider stripes of In-rich and In-poor zones: calculated energy variations show a strong tendency for N atoms to completely desert In-poor zones.
GaNAsBi Semiconductor Alloy with Temperature-Insensitive Bandgap
Authors: Yoshimoto Masahiro , Haung Wei , Feng Gan , Oe Kunishige 
Published: April 2011

ABSTRACTGaNyAs1−x−yBix alloys were grown by molecular beam epitaxy (MBE) using solid Ga, Bi, and As sources and nitrogen radicals generated from N2 in rf plasma. To achieve Bi incorporation into the epilayer, As flux was adjusted in a limited range on the brink of As shortage on the growing surface. GaNyAs1−x−yBix alloys lattice-matched to GaAs substrates with different photoluminescence (PL) peak energies were obtained. The GaNyAs1−x−yBix alloy lattice-matched to GaAs turned out to have the structure of Ga(N0.34Bi0.66)zAs1−z. The PL spectra showed that the PL peak energy of GaNyAs1−x−yBix alloy decreased with increasing Bi and N contents with redshift coefficients of ∼62 meV/%Bi and ∼130 meV/%N, respectively, at room temperature. The temperature dependence of the PL peak energy for GaNyAs1−x−yBix in the temperature range of 150∼300 K is much smaller than that of InGaAsP. The temperature coefficients of GaNyAs1−x−yBix bandgaps were governed by the GaBi molar fraction and decrease with increasing GaBi molar fraction.
Growth and Characterization of InGaNAs Quaternary Alloys for the Fabrication of Long Wavelength MSM Photodetectors on GaAs Substrates
Authors: Higgins Erle , Noad Julian , Gouin Francois , Coulas David 
Published: April 2011

ABSTRACTIn this paper, the optical and electrical properties of both as-grown and annealed thick InxGa1−xNyAs1−y layers grown by metal organic chemical vapour deposition (MOCVD) are presented. Through careful control of the trimetylyindium (TMIn), dimetylyhydrazine (DMHy), trimethylgallium (TMGa) and arsine (AsH3) precursors, lattice matching conditions were achieved for epitaxial layers containing up to 3% nitrogen (0≤y≤0.03) and 11% indium (0≤x≤0.11) with bandgap wavelengths to 1.3 μm. Nomarski optical microscopy and double crystal x-ray diffraction (XRD) measurements are used to investigate surface morphology, material quality and lattice-matched conditions. There is little or no 10K photoluminescence from the as-grown layers; alloy activation through rapid thermal annealing must be performed to obtain observable photoluminescence peaks. Annealing is also performed to reduce the resistivity of the as-grown layers. Once annealed, the undoped layers exhibited p-type carrier concentrations of 5.5×1017 cm−3 and mobilities of 50 cm2/Vs. The DC and frequency response performance characteristics of metal-semiconductor-metal (MSM) photodetectors fabricated on both as-grown and annealed InGaNAs layers are examined and compared to similar structures fabricated using GaAs and InGaAs/InP epitaxial materials.