bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Fe-Addition to Al-10Ti Alloy on Superplasticity at High-Strain Rates
Authors: Kum D. , Kim W. J. 
Published: April 2011

AbstractUltra-fine microstructure consisting of equiaxed Al-grains and aluminide particulate was produced by powder metallurgy process using gas-atomized powders of Al-10wt%Ti-2wt%Fe alloy. High strain rate superplasticity (HSRS) has been investigated at 873-923K and strain rates higher than 10−3s−1in tension, and total elongation up to 500% was observed at the strain-rate of 10−1s−1. The strain rate vs. flow stress behavior exhibits the typical aspect of HSRS such as the increase of strain-rate sensitivity exponent with increase in strain-rate and an apparent activation energy higher than that for lattice diffusion in aluminum. The concept of threshold stress has been incorporated to illustrate the HSRS behavior, where the stress exponent of 3 describes the experimental data. The determined threshold stress showed strong temperature dependency as in the case of a similarly processed Al-10wt%Ti alloy, which exhibited the stress exponent of 2 in the same testing conditions. Solute drag mechanism has been postulated for the Al-Ti-Fe alloy.
Superelastic Shape Memory Alloy For Seal Applications Produced by Low Pressure Thermal Spray Technology
Authors: Sickinger Albert , Teter Joseph P. 
Published: April 2011

AbstractThe objective of this development program was to demonstrate the feasibility of producing superelastic NiTi shape-memory alloy (SMA) foil material by the low pressure plasma spraying (LPPS) process for the development of robust, corrosion resistant and long life sealing technology.A conventional LPPS facility was retooled for the use of electric wire arc spraying and the process parameters were reconfigured. Foil specimens sprayed up to 1.5mm thickness showed good ductility after consolidation heat treatment at 950'C for 1 hour. Subsequent rolling of the foil specimens to a thickness of 0.5mm exhibited superelastic behavior. The amount of superelasticity will have to be determined. In addition, thin (0.2 mm) and thick (0.76mm) wall tubes have been produced in the 12.5mm diameter range. These samples were heat treated and subjected to Hot Isostatic Pressing (HIP). Metallographic examination revealed dense, solid microstructures after heat treatment and rolling, and hot isostatic pressing respectively.It was concluded, that this development established the feasibility to produce near net shape superelastic NiTi foil with a retooled Low Pressure Wire Arc Spraying (LPWAS) process, modified to permit substitution of NiTi-wire for NiTi-powder as feed stock.
Characteristics of Piezoelectric Ceramics at High Vibration Levels
Authors: Takahashi S. , Sasaki Y. , Umeda M. , Nakamura K. , Ueha S. 
Published: April 2011

AbstractNew piezoelectric power devices -such as ultrasonic motors, piezoelectric actuators and piezoelectric transformers- have been studied intensively in recent years. The piezoelectric ceramics in these devices are often subjected to a high level of vibration, and the electromechanical characteristics of piezoelectric ceramics at high vibration levels vary when changes in vibration level are accompanied by changes in temperature. The effects of temperature and of vibration level on specific electromechanical characteristics of typical piezoelectric ceramics were therefore separated by using two measurement methods: the continuous-voltage-wave method, which results in an increased temperature; and the burst-voltage-wave method, which does not. The elastic, dielectric and piezoelectric constants were found to be sensitive to temperature but comparatively insensitive to vibration level. Mechanical loss, however, was found to be a function of both temperature and vibration level.
Shape Memory Ceramics
Authors: Matsumura T. , Nakamura T. , Tetsuka M. , Takashina K. , Tajima K. , Nishi Y 
Published: April 2011

AbstractThree types of shape memory ceramics were introduced. They were the irreversible shape memory silica glass, the reversible shape memory bi-ceramics glass and reversible shape memory silica and Si-C-O glassy fiber samples (the small size change) induced by thermal expansion.
Switching Current in Pb(Zn1/3Nb2/3)O3-PbTiO3 Single Crystals
Authors: Belegundu Uma , Du Xiaohong , Uchino Kenji 
Published: April 2011

AbstractSwitching current measurements have been carried out on relaxorferroelectric single crystal-pure PZN, and the solid solution (1-x) Pb(Zni1/3 Nb2/3)O3 - x PbTiO3 with x= 0.04, 0.09, 0.10. Measurements have been done for crystallographic directions [001] and [111] for all these compositions. Switching times versus the applied field showed the following results. Pure PZN along [111] and 0.90PZN—O. 10PT along [001], and [111] showed an exponential dependence. Along [001] the PZN showed a linear fit. For solid solution single crystals-0.96PZN -0.04PT and 0.91PZN £ 0.09PT, a linear fit was obtained for the reciprocal switch times versus applied field for both the directions. If we draw a parallel picture with the reported barium titanate data, it appears that the polarization reversal is controlled by nucleation along [111]- spontaneous direction for PZN and [001], [111]for 0.90PZN - O.10PT. The mobility of the reversed domains controls the reversal along [001] for PZN and the solid solution single crystals with rhombohedral composition along [001] and [111]. The transient current curves showed two maximum points for crystals with x = 0.04 and 0.09. This is attributed to the co-existence of the two phases in 0.96PZN -0.04PT and 0. 91PZN - 0.09PT crystals.
Development of a MEMS Xylophone Bar Magnetometer Using Optical Interferometry for Detection
Authors: Miragliotta Joseph , Osiander R. , Champion J. L. , Oursler D. A. , Kistenmacher T.J. 
Published: April 2011

AbstractWe report the results of an optical interferometric study, which was designed to measure the magnetic-field induced displacement of a resonating xylophone bar MEMS magnetometer. The MEMS magnetometer is a Lorentz-force sensor, which transduces an alternating current and an orthogonal directed magnetic field into an alternating displacement of the xylophone bar. The Michelson interferometer system includes optics and electronics for active stabilization of the optical path length difference between the reference and sample beams. The active stabilization results in the ability to control or detect pathlength differences as small as ∼ 0.6 ×10−3 Å. With this level of operational sensitivity, the presence of a one nano Tesla magnetic field was found to produce a detectable bar displacement on the order of ∼10−3 Å. In addition to the high sensitivity, the interferometer photodetector displayed linear behavior over six decades of optical path length differences, which corresponded to a magnetic field dynamic range that spanned nano- to milli-Tesla amplitudes.
Mechanical Property Measurement of Electroplated Gold Microstructure Using Resonance Method
Authors: Baek Chang-Wook , Kim Yong-Kweon , Ahn Yoo-Min 
Published: April 2011

AbstractMechanical properties of electroplated gold microstructures were determined by measuring resonance frequencies of microbeams. Cantilever and bridge beam structures of different lengths were fabricated by electroplating surface micromachining technique, specially designed to realize an ideal fixed-boundary anchor. Fabricated beams were electrostatically excited and their resonance frequencies were measured by optical system composed of laser displacement meter with dynamic signal analyzer. Young's modulus, residual stress were calculated from the measured frequency data.
Effect of Buffer Electrodes in Crystallization of Zinc Oxide Thin Film for Thin Film Bulk Acoustic Wave Resonator
Authors: Yosho Y. , Tsukai N. , Inoue K. , Takeuchi M. , Nomura T. , Makino T. , Arai S. , Hata T. 
Published: April 2011

AbstractA thin film bulk acoustic wave resonator (TBAR) has been fabricated using a ZnO thin film on a SiO2 diaphragm by MEMs techniques. The ZnO/SiO2 structure TBAR can be designed to cancel a temperature coefficient of frequency (TCF) by the ZnO/SiO2 thickness ratio, because the TCF of ZnO is negative, and that of SiO2 is positive. The ZnO thin film on the SiO2 shows a c-axis orientation almost equivalent to that of the ZnO thin film on a glass substrate by RF sputtering. However, the crystallinity of the ZnO thin film is influenced by the surface conditions of substrates. ZnO thin films have been deposited on Au/Cr, Au/NiCr and Au/Ti. The Au/Ti/ZnO/Au/Ti/SiO2 structure TBAR shows the best resonant characteristics in this experiment. The resonant characteristics of the TBAR depend on the crystallinity of the ZnO thin film. The resonant resistance of the TBAR at 205MHz using a Au/Ti under electrode is about 10% less than that using an Au/Cr electrode. The x-ray diffraction result shows that the crystallinity of ZnO is greatly influenced by the crystallinity of the lower electrode. The buffer layer between an Au electrode and substrate has an influence on both the crystallinity of the ZnO thin film and the resonant characteristics of the TBAR through the Au electrode.
Preparation of High-Quality Ultra-Thin Gate Dielectrics by Cat-CVD and Catalytic Anneal
Authors: Satot Hidekazu , Izumit Akira , Matsumura Hideki 
Published: April 2011

AbstractThis paper reports a feasibility of Cat-CVD system for improvement in characteristics of ultra thin gate dielectrics. Particularly, the effects of post deposition catalytic anneal (Catanneal) by using hydrogen (H2)-decomposed species or NH3-decomposed species produced by catalytic cracking of H2 or NH3, are investigated. The C-V characteristics are measured by MIS diode for the 4.5nm-thick Cat-CVD SiNx and 8nm-thick sputtered SiO2 for comparison. The small hysteresis loop is seen in the C-V curve of both SiNx and SiO2 films as deposition. However, it is improved by the Cat-anneal using H2 or NH3, and the hysteresis loop completely disappears from the C-V curves for both films. This result demonstrates that the Cat-anneal is a powerful technique to improve quality of insulating films, such as Cat-CVD SiNx and even sputtered SiO2 films. In addition, the leakage current of SiNx, films with 2.8nm equivalent oxide thickness is decreased by several orders of magnitude than that of the conventional thermal SiO2 of similar EOT and the breakdown field is increased several MV/cm by Cat-anneal at 300°C.
Silicon Cleaning Methods Compared at Metal Concentrations Below 1E10 atoms/cm2
Authors: Ilardi Joseph , Saraswati Rajananda , Schwartzkopf George 
Published: April 2011

AbstractAn alkaline aqueous silicon wafer cleaner has been developed which reduces trace metal contamination levels on “p-type” unpatterned silicon wafers to below 1E10 atoms/cm2 without acidic cleaning. This patented technology uses a specially formulated buffering system consisting of an oxidation resistant chelating agent and salt of a weak acid. The aqueous cleaner maintains a stable pH of about 9.5 over a wide range of dilutions, temperatures, hydrogen peroxide concentrations and bath aging times. A single-step bath, megasonic bath or spray clean with this formulation leaves the chemical oxide on the silicon wafer surface free of particles, atomically smooth, free of organics and lower in trace metal contamination levels than similar surfaces cleaned with conventional formulations.An analytical method was developed which allows the reliable detection of trace metals on silicon wafer surfaces down to 1E8 atoms/cm2 for aluminum, calcium, copper, iron, nickel, sodium and zinc. The procedure uses an ICP-MS with a concentric nebulizer and a desolvator. The acids used were ultrapure to keep the blanks to a very minimum and analyses were run in a class 10 clean room. The trace metals on the wafer were extracted using known amounts of ultrapure acids and were directly aspirated using a special arrangement with the concentric nebulizer. The J.T. Baker cleaner was compared to and outperformed the conventional RCA-1&2 clean and dilute RCA-1&2 chemistries using ultrapure ammonium hydroxide, hydrochloric acid and hydrogen peroxide.
Aspects of Gas Phase Chemistry During Chemical Vapor Deposition of Ti-Si-N Thin Films With Ti(NMe2)4 (TDMAT), NH3, and SiH4
Authors: Amato-Wierda Carmela , Norton Edward T. , Wierda Derk A. 
Published: April 2011

AbstractSilane activation, predominantly in the gas phase, has been observed during the chemical vapor deposition of Ti-Si-N thin films using Ti(NMe2)4, tetrakis(dimethylamido)titanium, silane, and ammonia at 450°C, using molecular beam mass spectrometry. The extent of silane reactivity was dependent upon the relative amounts of Ti(NMe2)4and NH3. Additionally, each TDMAT molecule activates multiple silane molecules. Ti-Si-N thin films were deposited using similar process conditions as the molecular beam experiments, and RBS and XPS were used to determine their atomic composition. The variations of the Ti:Si ratio in the films as a function of Ti(NMe2)4 and NH3 flows were consistent with the changes in silane reactivity under similar conditions.
External Cavity Mid-Infrared Semiconductor Lasers
Authors: Le H. Q. , Lin C.-H. , Murry S. J. , Zheng J. , Pei S.-S. 
Published: April 2011

AbstractSb mid-IR laser can be used in external configuration to achieve wide wavelength tuning range. At low temperature, gain media with band-edge wavelengths between 3.3 to 4 pm have been demonstrated with wavelength tuning up to ∼9% of the center wavelength. Power output from few tens of mW to 0.2-W peak, 20-mW average was achieved. Type-II Sb laser promises the possibility of such performance at higher temperature, e. g. 200 K. However, significant trade-off must be considered between tuning range and power and efficiency. Optimization requires consideration of both basic wafer design and cavity geometry.
Photoconductive Properties of GaAs1−xNxDouble Heterostructures as a Function of Excitation Wavelength
Authors: Ahrenkiel R. K. , Mascarenhas A. , Johnston S. W. , Zhang Y , Friedman D. J. , Vernon S. M. 
Published: April 2011

AbstractThe ternary semiconductor GaAs1−xNxwith 0 < x < 0.3 can be grown epitaxially on GaAs and has a very large bowing coefficient. The alloy bandgap can be reduced to about 1.0 eV with about a 3% nitrogen addition. In this work, we measlired the internal spectral response and recombination lifetime of a number of alloys using the ultra-high frequency photoconductive decay (UHFPCD) method. The data shows that the photoconductive excitation spectra of the GaAs0.97N0.03alloy shows a gradual increase in response through the absorption edge near Eg. This contrasts with most direct bandgap semiconductors that show a steep onset of photoresponse at Eg. The recombination lifetimes frequently are much longer than expected from radiative recombination and often exceeded 1.0 µs. The data was analyzed in terms of a band model that includes large potential fluctuations in the conduction band due to the random distribution of nitrogen atoms in the alloy.
Infrared-Photovoltaic Responses of Ion-Beam Synthesized β-FeSi2/n-Si Heterojunctions
Authors: Maeda Yoshihito , Umezawa Kenji , Miyake Kiyoshi , Ohashi Kenya 
Published: April 2011

AbstractPhotoresponses of photovoltaic cells using ion-beam synthesized (IBS) polycrystalline p+-β-FeSi2/n-Si heterojunctions were examined in an infrared (IR) wavelength region. At room temperature, an evident photoresponse due to an internal photoemission from trap levels in β-FeSi2 with the threshold energy Φ=0.62 eV was observed at 0.6-0.87 eV. The pronounced increase of a photoresponse corresponding mostly to an interband transition in β-FeSi2 was observed at 0.87-1.1 eV. The maximum dominated by a surface recombination process appeared around ∼1.2 eV. The surface recombination rate of ∼104 cm/s was estimated. The quantum efficiency was ∼60 % in the 0.8-1.0 µm wavelength region and ∼14 % around the band-gap of βFeSi2.
Si1−xGex Bulk Crystals Growth and PN Junction Formation by Diffusing Phosphorus
Authors: Kato S. , Horikoshi T. , Ohkubo T. , Iida T. , Takano Y. 
Published: April 2011

AbstractThe bulk crystal of silicon germanium was grown by vertical Bridgman method with germanium composition, x, varying from 0.6 to 1.0. The temperature dependent variation of the mobility is indicative of alloy scattering dominantly for the bulk wafer. Phosphorus was diffused in as-grown p-type bulk wafer at 850 °C to form pn-junction, and the diffusion coefficient of phosphorus was evaluated as a function of x. The diffusion behavior of phosphorus in silicon germanium is closely correlated with the germanium self-diffusion with changing x. For specimens with lower content x, P concentration profiles indicated “kink and tail” shape, while it was not observed for higher x. For current-voltage characteristics measurement, an ideality factor was obtained.
Second-Harmonic Generation in Oriented CdSe-Nanocrystal-Doped Indium Tin Oxide Film and its Application to an Infrared Detector
Authors: Narazaki A. , Hirano T. , Sasai J. , Tanaka K. , Hirao K. 
Published: April 2011

AbstractSecond-harmonic generation in CdSe nanocrystals doped in indium tin oxide ( ITO ) films has been examined. The thin film samples were prepared by r.f. magnetron sputtering with ITO target on which CdSe chips were placed. The X-ray diffraction patterns of as-deposited films indicate that CdSe crystallites are precipitated in an amorphous ITO matrix, and they are preferentially oriented in the direction of (111) plane of zinc blende structure or (002) plane of wurtzite structure. The mean diameter of CdSe crystallite was estimated to be 3-5 nm using Scherrer's equation. Moreover, the CdSe crystallites grew with keeping its initial orientation when a dc voltage of 50 V/cm was applied in the direction parallel to the film surface. The application of the electric field effectively enhanced the second-harmonic intensity by two orders of magnitude compared to that of the as-deposited films. The second-order nonlinear coefficient d(2) for the electrically-treated specimen calculated on a basis of a modified Maker fringe theory is d31 = 3.0 × 10 pm/V at the wavelength of 1064 nm, which is comparable to d values reported for CdSe single crystal, d31 = 25 pm/V at 1054 nm and d33 =76 pm/V at 1064 nm.
Growth Processes of Hydrogenated Amorphous Silicon
Authors: Robertson John 
Published: April 2011

ABSTRACTThe surface and subsurface processes occurring during the growth of a-Si:H are analysed to understand why dangling bond defects and weak Si-Si bonds form. We argue that hydrogen elimination to form the Si-Si network is the rate limiting process at low temperature, and this leads to the creation of weak Si-Si bonds. Dangling bonds form subsequently from weak bonds by a defect pool type process. Plasma processes, such as ion bombardment, which dehydrogenate the surface layers, can reduce the weak bond density.
Near Infrared Detectors and Solar Cells Based on Microcrystalline Silicon Germanium
Authors: Krause M. , Stiebig H. , Carius R. , Wagner H. 
Published: April 2011

ABSTRACTMicrocrystalline silicon germanium alloys (ν-Si1−xGex:H) exhibit an enhanced optical absorption in the near infrared region with increasing germanium content. Therefore, the employment of this material as intrinsic absorber is a promising challenge for thin film technology in photovoltaics and sensorics. The influence of hydrogen dilution on the material and the performance of pin diodes prepared in a PECVD process with 10 % GeH4 in the gas phase is discussed. These results are compared with the characteristics of diodes prepared with higher germane content in the gas phase. With increasing germane content the solar cell parameters Voc and FF decrease and the deposition regime where good optoelectronic properties are observed is narrowed.
Negative Differential Resistance Characteristics of Silicon Nanocrystal Memory
Authors: Baik Seung Jae , Lim Koeng Su 
Published: April 2011

ABSTRACTTwo-dimensional (2D) Si quantum dot array was fabricated by oxidation of microcrystalline Si film deposited by photo chemical vapor deposition (photo-CVD). Average size of Si quantum dot was estimated to be 2.4nm and dot density 7 ∼ 8 ×1011cm−2. Nanocrystal memory device with this 2D quantum dot array demonstrated negative differential resistance characteristics and single charge tunneling phenomena, which was observed as stepwise decrease of gate transconductance. Interface states at the oxidized surface of quantum dots were assumed to explain temperature dependence characteristics. This new process is adequate for functional device application of nanocrystal metal-oxide-semiconductor (MOS) memory.
40 Years Trajectory of Amorphous Semiconductor Research
Authors: Hamakawa Yoshihiro 
Published: April 2011

ABSTRACTA review is given on a research trajectory of amorphous and microcrystalline semiconductors and their device applications proceeded since 1970. A brief explanation on the motivation to start amorphous semiconductor research is given to produce a new kind of synthetic semiconductor having continuous energy gap controllability with valency electron controllability through our experience of modulation spectroscopy in semiconductors.The first material we have challenged is Si-As-Te chalcogenide semiconductor which has a very wide vitreous region in Gibb's Triangle. A series of systematic experiments has been carried out in the terrestrial environment since 1971, and also within the TT-500A rocket experiment in 1980, and the Spacelab. J experiments FMPT (First Material Processing Test) project in 1992. The second material is hydrogenated amorphous silicon (a-Si:H) and its alloys started in 1976 just after the Garmisch Partenkirchen ICALS-6. With some basic research on the a-Si:H film deposition technology and film quality improvement, our continuous effort to improve the efficiency bore the tandem type solar cells in 1979, and also new products of a-SiC:H and a-SiGe:H in the early period of 1980s are described. These innovative device structures and materials have bloomed in the middle of 1980s in R & D phase such as a-SiC/a-Si heterojunction solar cells, a-Si/a-SiGe and also a-Si/poly-Si tandem type solar cells, and industrialized in recent few years. New kind of trials on full-color thin film light emitting devices has also been recently initiated with wide range of band gap controllability of a-SiC:H.The third material is microcrystalline silicon (µc-Si) and their alloys which gathers a tremendous R & D effort as a promised candidate for the bottom cell of the a-Si/µc-Si tandem solar cells aimed for the all-round plasma CVD process for the next age thin film photovoltaic devices. In the final part of presentation, a brief discussion will be given on a technological evolution from “bulk crystalline age” to “multilayered thin film age” in the semiconductor optoelectronics toward 21 century.
Microstructure Characterization of Amorphous Silicon Based Alloys by Inert Gas Effusion Studies
Authors: Beyer Wolfhard , Camargo Sergio S. , Saleh Rosari 
Published: April 2011

ABSTRACTIt is shown that inert gas effusion employing implanted neon and argon atoms is a useful tool for microstructure characterization of a-Si based alloys. The method measures sensitively interconnected voids and gives information about sizes of microstructure. Limitations of the method are discussed. The results show network reconstruction effects in a-Si:O:H and a-Si:C:H alloys as a function of annealing.