bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Beam Doping (Superdiffusion) in Damage-Free Regions of Semiconductors by the Kick-Out Mechanism (Secondary-Ion Mass Spectrometer and Photoluminescence Measurements)
Authors: Wada Takao , Fujimoto Hiroshi 
Published: October 2002

Zn atoms were doped into the damage-free regions of GaAs by a 750 keV electron
beam doping method at room temperature. The experimental structures were GaAs (layer 3)/Zn//Zn/GaAs (layer 1), whose Zn/GaAs consists of Zn evaporated layers on
GaAs wafers. The Zn overlayer surface is only in contact with another Zn substrate
surface. The surfaces of layer 3 (GaAs) were irradiated with a
fluence of ∼5×1017 electrons cm-2 at 100°C in N2 gas. The 750 keV electrons do not penetrate the Zn layers,
because of larger thickness for the ranges of electrons. The diffusion profiles of Zn into
GaAs were measured with a secondary-ion mass spectrometer. Photoluminescence
spectra for electron beam Zn-doped GaAs were investigated.
Excitonic Emissions under High Excitation of Hexagonal GaN Single Crystal Grown by Sublimation Method
Authors: Satoshi Kurai Satoshi Kurai , Akira Kawabe Akira Kawabe , Taiichi Sugita Taiichi Sugita , Shuichi Kubo Shuichi Kubo , Yoichi Yamada Yoichi Yamada , Tsunemasa Taguchi Tsunemasa Taguchi , Shiro Sakai Shiro Sakai 
Published: October 2002

Excitonic emission lines from hexagonal-structured GaN single crystals grown by the sublimation method have been studied at 4.2 K. A dominant I
2 line at 3.4706 eV, which is probably ascribed to the radiative recombination of an exciton bound to a neutral donor, has a linewidth of 2.1 meV under low excitation. Fine structures around 3.475 eV and 3.479 eV appear with increasing excitation power density. These positions correspond to those of A-free exciton and B-free exciton in strain-relaxed GaN crystal, respectively. A new line at 3.454 eV can be observed above 270 kW/cm2 and gradually shifts towards the low-energy side with a further increase in excitation power density. It is suggested that the origin of this line is due to the inelastic exciton-exciton interaction. The emission related to dense exciton gas was observed in the excitonic luminescence from bulk GaN for the first time.
Wear-Resistant Thin Films of Amorphous Carbon Nitride Prepared by Shielded Arc Ion Plating
Authors: Nobuhiro Tajima Nobuhiro Tajima , Hiroki Saze Hiroki Saze , Hiroyuki Sugimura Hiroyuki Sugimura , Osamu Takai Osamu Takai 
Published: October 2002

Amorphous carbon nitride (a-C:N) thin films were synthesized by means of shielded arc ion plating using a graphite target and pure nitrogen gas. The mechanical properties and chemical structures of these a-C:N films were studied through nanoindentation and X-ray photoelectron spectroscopic analysis. Nanohardness of the a-C:N film prepared at a substrate bias voltage of 0 V was ≈10 GPa. It was increased to 13–14 GPa when the substrate was biased negatively in the range of -100 to -500 V. The a-C:N film prepared at a bias of -300 V was particularly wear-resistant such that the film did not wear at all when rubbed with a diamond tip at a contact force of 20 µN. This highly wear-resistant a-C:N film was found to contain almost equal amounts of two C-N phases: β-C3N4-like and graphitelike phases.
Initial Measurements from an Ultrashort-Pulse Reflectometer on GAMMA 10
Authors: Kubota Shigeyuki , Onuma Tsuyoshi , Katoh Masayuki , Mase Atsushi , Tokuzawa Tokihiko , Oyama Naoyuki , Itakura Akiyosi , Hojo Hitoshi , Bruskin Leonid G. , Tamano Teruo , Yatsu Kiyoshi , Domier Calvin W. , Jr. andNeville C. Luhmann, 
Published: October 2002

Initial results from an ultrashort-pulse reflectometer
on the GAMMA 10 tandem mirror are
presented. The diagnostic uses an impulse generator (8 V, 65 ps full-width
at half maximum) as its microwave source, and the four-channel receiver system
measures the time-of-flight for ordinary-mode polarized reflected waves at
8, 9, 10 and 11 GHz. The reflectometer tracks electron density fluctuations
well over portions of the discharge, while overall values of the time-of-flight
are in rough agreement with calculated values using Abel-inverted profiles
from interferometry data. These results demonstrate the potential of the
current system for time-resolved electron density profile measurements on
GAMMA 10.
Large Free-Standing GaN Substrates by Hydride Vapor Phase Epitaxy and Laser-Induced Liftoff
Authors: Michael K. Kelly Michael K. Kelly , Robert P. Vaudo Robert P. Vaudo , Vivek M. Phanse Vivek M. Phanse , Lutz Görgens Lutz Görgens , Oliver Ambacher Oliver Ambacher , Martin Stutzmann Martin Stutzmann 
Published: October 2002

Free-standing GaN, nearly equal in area to the original
2 inch wafer, was produced from 250–300 µm thick GaN films
grown on sapphire by hydride vapor phase epitaxy (HVPE). The thick
films were separated from the growth substrate by laser-induced
liftoff, using a pulsed laser to thermally decompose a thin layer
of GaN at the film-substrate interface. Sequentially scanned
pulses were employed and the liftoff was performed at elevated
temperature (>600°C) to relieve postgrowth bowing. After
liftoff, the bow is only slight or absent in the resulting free
GaN.
Improvement of 1.5 µm Photoluminescence from Reactive Deposition Epitaxy (RDE) Grown β-FeSi 2 Balls in Si by High Temperature Annealing
Authors: Takashi Suemasu Takashi Suemasu , Yusuke Iikura Yusuke Iikura , Tetsuo Fujii Tetsuo Fujii , Ken'ichiro Takakura Ken'ichiro Takakura , Noriyoshi Hiroi Noriyoshi Hiroi , Fumio Hasegawa Fumio Hasegawa 
Published: October 2002

We found that 900°C annealing was a very effective way to improve the 1.5 µm photoluminescence (PL) from β-FeSi2 balls with about 100 nm diameter grown by reactive deposition epitaxy (RDE) and embedded in Si crystals by molecular beam epitaxy (MBE).
The full-width at half maximum (FWHM) of the 1.5 µm PL peak was about 1/4 of that of the as-grown sample, after annealing at 900°C for 14 h. This was attributed to improvement of the β-FeSi2 quality. The FWHM of an X-ray diffraction β-FeSi2 (800) peak decreased from 0.24° to 0.14° by the annealing.
35 nm Metal Gate p-type Metal Oxide Semiconductor Field-Effect Transistor with PtSi Schottky Source/Drain on Separation by Implanted Oxygen Substrate
Authors: Wataru Saitoh Wataru Saitoh , Shigeharu Yamagami Shigeharu Yamagami , Atsushi Itoh Atsushi Itoh , Masahiro Asada Masahiro Asada 
Published: October 2002

P-type metal oxide semiconductor
field-effect transistors with PtSi Schottky sources/drains
with a 35-nm long metal gate
were fabricated on a separation by implanted oxygen substrate by
electron-beam lithography and a self-aligned silicide process.
The drain current was -176 µA/µm and
the transconductance was 390 mS/mm
at V
DS = V
GS = -1.5 V.
For these devices, comparable drivability
to conventional metal oxide semiconductor
field-effect transistors was achieved.
The on/off ratio was improved using a very thin
silicon-on-insulator structure.
Molecular-Beam Epitaxial Growth of (001) Cr/Al/Cr/Al Quadrilayer Superlattice Containing One-Monolayer-Thick Cr Layers
Authors: Toshiki Kingetsu Toshiki Kingetsu , Yasuhiro Kamada Yasuhiro Kamada , Masahiko Yamamoto Masahiko Yamamoto 
Published: October 2002

We studied the growth behavior and structures of a molecular-beam-epitaxy-grown (001) Cr/Al/Cr/Al quadrilayer superlattice that contains one-monolayer-thick Cr layers, using in situ reflection high-energy electron diffraction and ex situ X-ray diffraction. We found that the quadrilayer superlattice grows epitaxially through many quadrilayer depositions to the top layer of the superlattice, in contrast to the previous finding that epitaxial growth is unstable upon deposition of (001) Al/Cr bilayer superlattices that contain Cr layers whose thickness is two monolayers or less.
Preparation of Tungsten Nitride on Alumina by Chemical Vapor Deposition
Authors: Nagai Masatoshi , Hirano Naoya , Omi Shinzo 
Published: October 2002

Tungsten nitride was synthesized on γ-alumina using a chemical vapor deposition method in a stream of WCl6, NH3, H2, and Ar at temperatures of 773 to 973 K under 70 Pa. The surface area of the W2N/Al2O3 system decreased from 178 to 140 m2 g-1 with increasing tungsten loading. The pore volume decreased with increasing deposition of W2N with a constant distribution of pore size. The X-ray diffraction analysis showed the formation of β-W2N (100) and (111) phases in the 4.9 wt% W2N/Al2O3 but not in the 1.2 and 3.3 wt% W2N/Al2O3. From the X-ray photoelectron spectroscopy analysis, the N 1s/W 4f atomic ratio increased from 1.3 to 1.6 for the 1.2 to 4.9 wt% W2N/Al2O3. W0, W2+, and W4+ were dominant for the 4.9 wt% W2N/Al2O3.
Material Losses and Compositional Changes in Two-Step Processed CuInSe2 Thin Films
Authors: Alberts V. , Klenk M. , Bucher E. 
Published: October 2002

Material losses and the resulting compositional changes in two-step processed chalcopyrite thin films are widely discussed topics in literature. In this study, metallic precursors were selenized in H2Se/Ar at a wide range of processing temperatures between 300°C and 600°C. The composition of the resulting films at different stages of processing were analyzed by electron probe microanalysis (EPMA) and X-ray fluorescence (XRF). Comparison of EPMA and XRF data from identical selenized samples revealed a discrepancy in composition at temperatures at or above a critical point around 400°C. In contrast to the loss of In indicated by EPMA measurements, XRF analysis revealed that the Cu and In Kα1,2 intensity values remained virtually constant, irrespective of the selenization conditions (i.e. no evidence of material losses). The use of more surface sensitive Lα1 line scans clearly revealed a segregation of In away and Cu towards the upper part of the layer with increasing selenization temperature. Based on these results the commonly reported compositional shift due to material losses is interpreted as a measurement artifact of the EPMA technique under typical measurement conditions for two-step processed chalcopyrite absorber films.
CHF3 Plasma Treatment of Si Field Emitter Arrays For No Damage Vacuum Packaging
Authors: Masayoshi Nagao Masayoshi Nagao , Hisao Tanabe Hisao Tanabe , Takashi Matsukawa Takashi Matsukawa , Seigo Kanemaru Seigo Kanemaru , Junji Itoh Junji Itoh 
Published: October 2002

Si field emitter arrays (FEAs) are promising cold cathodes for field emission displays (FEDs). The emission current from the Si FEAs, however, is known to decrease significantly after the vacuum-packaging process based on the frit sealing technique. In this work, we have investigated the mechanism of the current decrease and found that CHF3 plasma treatment of the tip surface was sufficiently effective to prevent the problem. In the experiment, the Si FEAs were exposed to the CHF3 plasma for 15 s and then treated by the same process as that for the frit sealing at various temperatures. No changes in the emission current were observed before and after the frit sealing process at temperatures up to 430°C. Details of the CHF3 plasma treatment are described.
iD PHOTO System –Digital Photo Media for Still Cameras–
Authors: Watanabe Hiroshi , Ichiura Syuichi , Kawakami Kouichi 
Published: October 2002

We developed a 50-mm-diameter magnetooptical disk system, iD PHOTO as a next-generation system for digital still cameras. The iD PHOTO system is based on the advanced storage magneto optical disk (AS-MO) standard, [rf1,rf2,rf3,rf4] and its media has a maximum capacity of 730 MB on a 50-mm-diameter single-sided disk, which exceeds the compact disc (CD) capacity, while being the world's smallest [rf5] rewritable optical disk. Using this system, it is possible to rewrite data at a high speed of more than 20 Mbps over one million times and moreover, it is suitable for saving data over long periods. Employing the magnetic field modulation (MFM) recording method and the center-aperture-detection (CAD)-type magnetic superresolution (MSR) readout method, the iD PHOTO system realizes high-density recording. The non return to zero inverted plus (NRZI+) modulation and the external clocking system enable high-capacity user data. Finally, we show that the read and write characteristics, which are sufficient for realizing a stable system, are obtained using external clocking and the CAD-type MSR readout method.
Selective Growth of GaN/AlGaN Microstructures by Metalorganic Vapor Phase Epitaxy
Authors: Tomonobu Kato Tomonobu Kato , Yoshio Honda Yoshio Honda , Yasutoshi Kawaguchi Yasutoshi Kawaguchi , Masahito Yamaguchi Masahito Yamaguchi , Nobuhiko Sawaki Nobuhiko Sawaki 
Published: October 2002

A GaN/AlGaN double heterostructure was fabricated on the (1101) facets of a GaN triangular structure prepared by selective area growth by metalorganic vapor phase epitaxy. The photoluminescence (PL) and cathode luminescence (CL) spectra were investigated to characterize the structure. It was found that the PL peak wavelength due to the GaN quantum well is dependent on the well thickness. However, the Al composition of the AlGaN layer is dependent on the position on the (1101) facet. The anomalous gradient of the composition is attributed to the difference in the diffusion coefficients of Al and Ga on the surface.
Optimization of Focal Position of Ultrasonic Beam in Measurement of Small Change in Arterial Wall Thickness
Authors: Masaru Watanabe Masaru Watanabe , Hiroshi Kanai Hiroshi Kanai 
Published: October 2002

We have previously developed a method for measurement of a small change in thickness of the arterial wall during a single cardiac cycle [H. Kanai, M. Sato, Y. Koiwa and N. Chubachi: IEEE Trans. UFFC 43 (1996) 791]. The resultant change in thickness is shown to be useful for the in vivo assessment of the regional elasticity of the arterial wall. Although the accuracy of the measurement of the change in thickness is found to be within 1 µm, it is affected by the interference of ultrasonic pulses. In this study, we simulate the propagation of ultrasonic pulses transmitted and received by a linear probe. In the simulation experiments, the ultrasonic pulses generated by a computer are reflected by a tube, which has a small change in wall thickness of 10 µm. The optimum focal position of the ultrasonic beam is determined by evaluating the root-mean-square (rms) error in the measured change in thickness.
Nonlinear Optical Absorption in the AgOx-Type Super-Resolution Near-Field Structure
Authors: Ho Fu Han , Lin Wei Yi , Chang Hsun Hao , Lin Yu Hsaun , Liu Wei-Chih , Tsai Din Ping 
Published: October 2002

Nonlinear optical absorption in the AgO
x
-type super-resolution near-field structure [glass/ZnS–SiO2 (170 nm)/AgO
x
(15 nm)/ZnS–SiO2 (40 nm)] was investigated using a confocal Z-scan technique with a continuous He–Ne laser. The transmittance Z-scan shows that the sample undergoes a phase transition with increasing incident laser power. The phase transition of the sample with higher incident laser power is due to permanent local structure damage caused by the laser heating process.
Mössbauer Effect of Fe Particles in Metal Audio Tape
Authors: Kohmoto Osamu , Hanafusa Toshiki , Yokoyama Masaru , Haneda Koichi 
Published: October 2002

The composition of the core of the magnetic pigment of an audio tape has been determined to be 2 at.% Co–1.8 at.% Ni–Fe by the Mössbauer technique and X-ray fluorescence analysis. The hyperfine field H
hf is 336±2 kOe, which is slightly stronger than that of pure Fe.
Performance of Ge–Sb–Bi–Te–B Recording Media for Phase-Change Optical Disks
Authors: Lee Chain-Ming , Yen Wen-Shin , Liu Ren-Haur , Chin Tsung-Shune 
Published: October 2002

We investigated the physical properties of GeSbBiTeB materials and examined the feasibility for phase change recording. The studied compositions were Ge4Sb0.5Bi0.5Te5 and Ge2Sb1.5Bi0.5Te5 with B doping. The coexistence of Bi and B atoms into both Ge4SbTe5 and Ge2Sb2Te5 lattice maintains single fcc structure without phase separation. The Bi substitution shows benefits in decreasing crystallization temperature and activation energy, however the reflectivity is slightly reduced. [rf3] With small amount addition of boron about 1 at.%, the reflectivity can be increased. [rf2] Conventional 4-layer structure of digital versatile disk-random access memory (DVD-RAM) 2.6 GB format was used to prepare the disks for dynamic characterization and overwrite cyclability evaluations. The disk with Ge4Sb0.5Bi0.5Te5(B) recording layer shows large noise fluctuation and low overwrite erase ratio, suggesting that the crystallization speed is still insufficient. While the disk with Ge2Sb1.5Bi0.5Te5(B) recording layer shows lower writing and erasing powers, stable noise level and high overwrite erase ratio, indicating the capability for DVD-RAM applications. The effect of B doping was verified to enhance the signal amplitude and modulation.
Dielectric and Piezoelectric Properties of (A0.5Bi0.5)TiO3–ANbO3 (A=Na, K) Systems
Authors: Wada Takahiro , Toyoike Kouji , Imanaka Yousuke , Matsuo Yoshihiro 
Published: October 2002

The microstructural, dielectric and piezoelectric properties of the (Na0.5Bi0.5)TiO3–NaNbO3 and (K0.5Bi0.5)TiO3–KNbO3 systems were studied in order to find new lead-free piezoelectric ceramic materials. In the (1-X) (K0.5Bi0.5)TiO3–(X) KNbO3 system, it was confirmed from the measurements of the electromechanical coupling factor, K
p, that piezoelectricity occurred within the wide compositional range between X=0 and 0.35. The sample with X=0.075 showed a maximum K
p of 15.1%. However, the expected morphotropic phase boundaries were not found in the (Na0.5Bi0.5)TiO3 or (K0.5Bi0.5)TiO3 rich side of the solid solution systems.
Formulation of a Viscoelastic Stress Problem Using Analytical Integration and Its Application to Viscoelastic Oxidation Simulation
Authors: Uchida Tetsuya , Nishi Kenji 
Published: October 2002

Formulation of a viscoelastic stress problem adopting an analytical integration scheme, which was originally proposed by Peng and co-authors [Proc. Symp. Process Physics and Modeling in Semiconductor Technology, Manchester, 1991, p. 772; COMPEL 10 (1991) 341], is given in a complete form. This formulation includes the treatment of initial strain, an implicit solution method, and improvement of the solution by successive iteration. According to the formulation, a two-dimensional oxidation program is made. Through the calculations of oxidation of a simple test structure, it is reconfirmed that numerical instability can be improved by adopting the scheme of Peng and co-authors [Proc. Symp. Process Physics and Modeling in Semiconductor Technology, Manchester, 1991, p. 772; COMPEL 10 (1991) 341]. Other aspects of the behavior of the solution, including the dependence of the solution on the magnitude of time steps, are also shown.
The Resistance of a High-Current Pulsed Discharge in Nitrogen
Authors: Takaki Koichi , Akiyama Hidenori 
Published: October 2002

The primary objective of this article is to propose a method for accurate prediction of the resistance of a high-current pulsed arc discharge. The nine theoretical and empirical formulas of arc resistance, which have been reported, are compared using the measured values of arc resistance for unipolar arc discharges in nitrogen gas with various maximum currents. The arc resistance was obtained accurately by solving the circuit equation using measured values of the current and breakdown voltage. Each arc resistance equation was numerically evaluated and then normalized by the arc resistance at the time of maximum arc current. The results indicated that Kushner et al..'s predictions [rf1] provided the best overall results with the lowest accumulation of errors. Additionally, the measured arc resistance takes the minimum value at the time of arc maximum current, and the value can be expressed by a function of the maximum current.
Near-Synonymy and Lexical Choice
Authors: Edmonds Philip , Hirst Graeme 
Published: October 2002

We develop a new computational model for representing the fine-grained meanings of near-synonyms and the differences between them. We also develop a lexical-choice process that can decide which of several near-synonyms is most appropriate in a particular situation. This research has direct applications in machine translation and text generation. We first identify the problems of representing near-synonyms in a computational lexicon and show that no previous model adequately accounts for near-synonymy. We then propose a preliminary theory to account for near-synonymy, relying crucially on the notion of granularity of representation, in which the meaning of a word arises out of a context-dependent combination of a context-independent core meaning and a set of explicit differences to its near-synonyms. That is, near-synonyms cluster together. We then develop a clustered model of lexical knowledge, derived from the conventional ontological model. The model cuts off the ontology at a coarse grain, thus avoiding an awkward proliferation of language-dependent concepts in the ontology, yet maintaining the advantages of efficient computation and reasoning. The model groups near-synonyms into subconceptual clusters that are linked to the ontology. A cluster differentiates near-synonyms in terms of fine-grained aspects of denotation, implication, expressed attitude, and style. The model is general enough to account for other types of variation, for instance, in collocational behavior. An efficient, robust, and flexible fine-grained lexical-choice process is a consequence of a clustered model of lexical knowledge. To make it work, we formalize criteria for lexical choice as preferences to express certain concepts with varying indirectness, to express attitudes, and to establish certain styles. The lexical-choice process itself works on two tiers: between clusters and between near-synonyns of clusters. We describe our prototype implementation of the system, called I-Saurus.
Searching with Unilateral Neglect
Authors: Pavlovskaya Marina , Ring Haim , Groswasser Zeev , Hochstein Shaul 
Published: October 2002

Abstract
We address two longstanding conflicts in the visual search and unilateral neglect literature by studying feature and conjunction search performance of neglect patients using laterally presented search arrays. The first issue relates to whether feature search is performed independently of attention, or rather requires “spread attention”. If feature search is “preattentive,” it should survive neglect. However, we find neglect effects for both feature and conjunction search, suggesting that feature search, too, has an attentional requirement. The second controversy refers to the space-or object-based nature of neglect following unilateral right-hemisphere parietal lobe damage. If neglect were a purely spatial phenomenon, then we would expect no detriment in performance in the right (nonneglect) field, and diminished performance for the whole left (neglect) field. On the other hand, if neglect were purely object-based, we would expect diminished performance on the left side of the search array, irrespective of its location in the visual field. We now demonstrate a combination of strong object-based and space-based neglect effects for conjunction search with laterally placed element arrays, suggesting that these two mechanisms work in tandem.