bluuebunny/crossref_metadata_2025 huggingface dataset:
Galvanomagnetic Behavior of Hot Electrons in Semi-Insulating GaAs
Authors: Hirohata Toru , Suzuki Tomoko , Kazutoshi Nakajima Kazutoshi Nakajima , Yoshihiko Mizushima Yoshihiko Mizushima
Published: February 2005

A new behavior of highly accelerated hot electrons in a magnetic field is observed in semi-insulating GaAs (S.I.GaAs). In an electric field at a few kV/cm, the conduction current in S.I.GaAs increases steeply. The abrupt current increase has been interpreted by the trap-filling model of Lampert. The abrupt current increase shows interesting behavior in a magnetic field. By magnetic field application (at ∼0.3 T), the current increment is cut off. This cutoff behavior requires a new concept of the conduction mechanism in S.I.GaAs. This report suggests that cyclotron cutoff occurs. It implies that the drifting electrons suffer no scattering, just as in vacuum. The scattering relaxation time of an electron is estimated to be extremely long, such as 50 ps.
The Effect of Dipolar Interactions on the Susceptibility Peaks in a Solidified Ferrofluid
Authors: Nabil Y. Ayoub Nabil Y. Ayoub
Published: February 2005

A number of magnetite (Fe3O4) ferrofluids with volume concentrations of ε=0.01, 0.02, 0.03, 0.04, 0.06 and 0.08 have been prepared by diluting a stock fluid of M
s=43 kA/m. These samples were frozen in zero magnetic field, and the variation of the initial susceptibility with temperature was measured for each sample. We find, experimentally, that a maximum occurs at T
p in the initial susceptibility-versus-temperature curve. T
p moves to higher values as the concentration of the ferrofluid increases. A theoretical model derived for a noninteracting fine particle system in a solid matrix along with a semiempirical hypothesis for the effect of the interparticle interaction on the anisotropy constant seems to correctly predict the peak in the susceptibility as well as the effect of the concentration on the temperature of the peak.
Polymer Dissolution Characteristics of Radiation-Induced Grafted Resist in X-Ray Lithography
Authors: Oizumi Hiroaki , Yasunari Sohda Yasunari Sohda , Kozo Mochiji Kozo Mochiji
Published: February 2005

Dissolution characteristics of grafted resist by X-ray irradiation are investigated. Poly(phenyl methacrylate) (PPhMA) which is used as a base resist is grafted by acrylic acid after X-ray exposure. The developed resist pattern was found to be significantly tapered with an increase in development time. Such a deterioration is attributed to swelling of the resist polymer and dissolution of less fully grafted components by developer. The swelling and dissolution of grafted resist during development is drastically minimized by the formation of a cross-linked structure in the grafted resist by thermal dehydration of acrylic acids. As a result, a grafted resist pattern with feature size as small as 0.3 µm is successfully obtained at the high X-ray sensitivity of 50 mJ/cm2.
Optically Writable and Erasable Memory in Semi-Insulating GaAs
Authors: Hirohata Toru , Tomoko Suzuki Tomoko Suzuki , Yoshihiko Mizushima Yoshihiko Mizushima
Published: February 2005

A new optical memory is found in semi-insulating GaAs (S.I. GaAs). This memory phenomenon appears when the electric field in S.I. GaAs is higher than 1 kV/cm. The electrical conductivity changes reversibly with light irradiation. Both turn-on and turn-off functions are controlled by selecting the wavelength. The mechanism of this optically controlled memory is discussed in terms of an electron trap and a carrier injection.
Effects of a Negative Self-Bias on the Growth of Cubic Boron Nitride Prepared by Plasma Chemical Vapor Deposition
Authors: Yokoyama Haruki , Masaki Okamoto Masaki Okamoto , Yukio Osaka Yukio Osaka
Published: February 2005

Microcrystalline cubic BN films have been prepared on a Si substrate by plasma chemical vapor deposition. The formation of the cubic BN phase in the films necessitated an appropriate negative self-bias on the substrate electrode. Effects of the negative self-bias on the growth of the cubic phase were studied. The dependence of the deposition rate and etching rate of the films on a negative self-bias shows that the cubic phase is generated by the precursors of radical or ion species induced by an ion current in a plasma, and the deposition rate is determined by the generation rate due to these precursors and the etching rate of the cubic phase. In contrast with this, the generation rate of the hexagonal BN phase is independent of the ion current in a plasma.
A New Chemical Method of Preparing Semiconducting MoX2 (X=S, Se) Thin Films
Authors: Krishna Chandra Mandal Krishna Chandra Mandal , Oumarou Savadogo Oumarou Savadogo
Published: February 2005

We report a new chemical method for preparing semiconducting MoX2 (X=S, Se) thin films on glass substrates. For MoS2 deposition, an ammine complex of Mo (VI) ions, thioacetamide and hydrazine hydrate solutions was used, while for MoSe2 films, sodium selenosulphate solution replaced thioacetamide, and other reagents remained unchanged. Structural, optical and electrical properties of the as-deposited and annealed films have been studied.
A Monte Carlo Simulation of Ion-Induced Kinetic Electron Emission with a Stochastic Excitation of Electrons in Solids
Authors: Kawata Jun , Ohya Kaoru , Mori Ichiro
Published: February 2005

A Monte Carlo simulation is performed for the study of the proton-induced kinetic secondary electron emission from solids. In this simulation, the excitation of conduction electrons in solids is stochastically treated by using the excitation function with the Lindhard dielectric theory. The calculated electron yields are about 30 percent larger than experimental yields at incident energy of 1 keV. The simulation, however, enables the calculation of angular and energy distributions of emitted electrons; the angular distribution calculated follows a cosine law. The energy distribution peaks at an energy of 2∼3 eV, which is consistent with the experimental ones, while the FWHM (full width at half-maximum) of the calculated distribution is larger than those. In addition, the depth distribution of secondary electrons is analogous to that obtained with electron bombardment.
A Proposal for Determination of Photopeak Areas of 60Co by the Sum-Peak Method
Authors: Takao Kawano Takao Kawano , Hiroshi Ebihara Hiroshi Ebihara
Published: February 2005

The sum-peak method can be applied to the determination of the disintegration rate of a 60Co source when areas under the two photopeaks (γ1: 1173 keV, γ2: 1332 keV), the sum peak, and the whole spectrum are measurable. It is difficult to obtain the exact photopeak areas through the use of a NaI(Tl) detector because the two photopeaks overlap somewhat and a part of the area under Compton scattering of γ2 also overlaps under the photopeak of γ1. In this paper, a precise method to determine the photopeak areas is proposed, which is the elimination of Compton scattering by using a 22Na spectrum. The sum-peak method is perfectly effective using the photopeak areas determined by this method.
Test of Two-Dimensional Position Sensitive Silicon Detector for Cosmic Ray Telescope by a Light Pulser
Authors: Kato Chihiro , Yoneda Akira , Munakata Kazuoki , Takashi Imai Takashi Imai , Tsuyoshi Kohno Tsuyoshi Kohno
Published: February 2005

In order to measure the distortion pattern of a large two-dimensional Position Sensitive silicon Detector (PSD), we tried a simple method using a light pulser instead of high energy particles from an accelerator. The obtained distortion pattern is quite similar to that from accelerator beams. We conclude that a light pulser can be used for this measurement. This simple method is relatively very easy considering the tight accelerator machine-time.
Growth and Properties of Low Pressure Chemical-Vapor-Deposited TiN for Ultra Large Scale integration
Authors: Arthur Sherman Arthur Sherman
Published: February 2005

This paper reviews recent studies of the low-temperature chemical vapor deposition of titanium nitride thin films suitable for ULSI applications. In addition to the comprehensive studies available for films grown thermally from TiCl4 and NH3, films deposited from organometallic precursors are discussed, as well as those derived from plasma-enhanced techniques. Two applications of such films for ULSI are as a diffusion barrier between different conductors, and as a nucleation layer for CVD tungsten. Properties of LPCVD TiN for these applications, are covered including film conformality, effectiveness as a diffusion barrier, contact resistance, nucleation of tungsten, and the influence of any residual chlorine.
Single-Target Sputtring Process for Lead Zirconate Titanate Thin Films with Precise Composition Control
Authors: Torii Kazuyoshi , Kaga Toru , Kushida Keiko , Hiroshi Takeuchi Hiroshi Takeuchi , Eiji Takeda Eiji Takeda
Published: February 2005

The influence of growth conditions on rf-magnetron sputtered lead zirconate titanate (or PZT) thin films has been investigated, and the structural and electrical properties of PZT thin films have been examined. It was found that the Pb content in a sputtered film is proportional to rf power, thereby making it possible to control the film composition precisely. A well-crystallized perovskite structure was obtained by postdeposition annealing at 590°C. A stoichiometric film (i.e., Pb/Zr+Ti=1) had a dielectric constant value of 1180.
Effect of Silicon Wafer In Situ Cleaning on the Chemical Structure of Ultrathin Silicon Oxide Film
Authors: Terada Naozumi , Ogawa Hiroki , Moriki Kazunori , Teramoto Akinobu , Makihara Koji , Morita Mizuho , Ohmi Tadahiro , Takeo Hattori Takeo Hattori
Published: February 2005

The effect of silicon wafer in situ cleaning on the chemical structures of thermally grown silicon oxide films was studied by X-ray photoelectron spectroscopy and scanning tunneling microscopy. After the silicon wafer in situ cleaning was performed by the decomposition of native oxides in high vacuum, the nearly 1.6-nm-thick thermal oxides were formed in dry oxygen at 800°C. If the heating time for the decomposition of native oxides was too short, intermediate states transformed from native oxides were found to remain on the surface of the oxide films. On the other hand, if the heating time was too long, the amount of intermediate states at the interface was found to increase as a result of the increase in interface roughness. The optimum condition for in situ cleaning is heating at 900°C for 30 minutes in high vacuum.
Visible Photoluminescence of Porous Si and Its Related Optical Properties
Authors: Koyama Hideki , Araki Minoru , Yuko Yamamoto Yuko Yamamoto , Nobuyoshi Koshida Nobuyoshi Koshida
Published: February 2005

Visible photoluminescence (PL) characteristics of porous silicon (PS) layers have been studied in relation to photoconduction and optical absorption spectra. The PS layers are formed on p- and n-type Si wafers by electrochemical and photoelectrochemical anodization in HF solutions. Some intrinsic correlations are observed between the peak wavelength of PL spectra and the anodization parameters. Other macroscopic observations show that both the photoconductivities and the fundamental absorption edges of PS layers are present in the visible region. This evidence suggests that the optoelectronic properties of PS are strongly modulated by the quantum size effect in microstructures of the PS.
A Novel Fabrication Technique of Multilayer Stacked Silicon-on-Insulator Structure Applicable to Three-Dimensional ICs
Authors: Kawai Kazuhiko , Nakanishi Shiroh , Ogata Hidenori , Yamaji Toshifumi , Nobuhiko Oda Nobuhiko Oda , Kiyoshi Yoneda Kiyoshi Yoneda
Published: February 2005

In this study, in order to investigate the feasibility of three-dimensional ICs fabricated using the combined techniques of lateral-solid phase epitaxy (L-SPE) and selective epitaxial growth (SEG) of Si, we fabricated a 5-layer stacked SOI structure and studied its characteristics. In this procedure, both epitaxy of Si for SEG on seeded windows and deposition of amorphous-Si for L-SPE were performed using ultra-low-pressure chemical vapor deposition. As a result, all single-crystalline SOI regions on each stacked layer exhibit the same graded crystallinity. We also fabricated n-channel metal oxide semiconductor field effect transistors onto the top layer. A maximum µFE of 617 cm2/(V·s) was obtained. This is the first report on the single-crystalline 5-layer stacked SOI structure.
Amorphization Processes in Ion Implanted Si: Temperature Dependence
Authors: Motooka Teruaki , Kobayashi Fumihiko , Fons Paul , Tokuyama Takashi , Suzuki Tadashi , Natsuaki Nobuyoshi
Published: February 2005

Temperature dependence of amorphization processes in ion-implanted Si has been investigated using Raman spectroscopy together with cross-sectional transmission microscopy. The crystal Si Raman peak decreased and the amorphous Si (a-Si) peak became predominant as the substrate temperture was decreased from 23°C to -200°C during 200 keV Si+ ion implantation with a dose of 5×1014 cm-2. Based on the analysis of bond angle deviations derived from the a-Si peaks, we have proposed a model in which an accumulation of small defects induces amorphization at low temperatures, while at higher temperatures larger defect complexes are formed and an accumulation of them gives rise to defected amorphous Si.
Analysis of Smear Noise in Interline-CCD Image Sensor with Gate-Free Isolation Structure
Authors: Ono Hideyuki , Ozaki Toshifumi , Haruhiko Tanaka Haruhiko Tanaka , Yoshifumi Kawamoto Yoshifumi Kawamoto
Published: February 2005

A gate-free isolation structure for smear noise suppression is proposed for an interline transfer charge-coupled device (IL CCD) image sensor. Analysis of the smear components shows that the signal-to-smear ratio in the proposed structure is 30 dB larger than that in a conventional structure, and is comparable to those of frame interline transfer (FIT) CCDs, while the isolation and breakdown characteristics of the proposed structure are similar to those of the conventional structure. These results indicate that the high-definition interline-CCD image sensors are promising for HDTV applications.
BF2
+ Ion Implantation into Very-Low-Temperature Si Wafer
Authors: Takakura Masaru , Kinoshita Tsuyoshi , Uranishi Tadashi , Miyazaki Seiichi , Koyanagi Mitsumasa , Masataka Hirose Masataka Hirose
Published: February 2005

BF2
+ ions at 30 keV were implanted into silicon wafers held at -100°C or room temperature. The recrystallization process of the implanted wafers was examined by Rutherford backscattering (RBS) and Raman scattering. The value of χmin for wafers implanted at -100°C and annealed at 600°C is 0.05, close to that of crystalline Si, while it is 0.08 for the room-temperature implantation. The Raman spectrum for the case of low-temperature implantation also exhibits a smaller amount of residual defects than that for the room-temperature implantation.
Generation Current Reduction at Local Oxidation of Silicon Isolation Edge by Low-Temperature Hydrogen Annealing
Authors: Kimura Mikihiro , Kaoru Motonami Kaoru Motonami , Yasuhiko Onodera Yasuhiko Onodera
Published: February 2005

The effect of low temperature hydrogen annealing (LTHA) in reducing the generation current at the local oxidation of silicon (LOCOS) isolation edge can be successfully investigated by C-t measurement of metal-oxide-semiconductor (MOS) capacitors with varying periphery-to-area ratio. The generation current, at the LOCOS isolation edge, can then be measured by the separation of the generated peripheral current and the surface and bulk current generated under the gate electrode. As a result, it becomes clear that the generation current is strongly reduced by annealing at a temperature below 400°C, but at 450°C the reduction is rather small.
A Novel Atomic Layer Epitaxy Method of Silicon
Authors: Imai Shigeru , Takagi Satoru , Osamu Sugiura Osamu Sugiura , Masakiyo Matsumura Masakiyo Matsumura
Published: February 2005

A new atomic layer epitaxy (ALE) method of silicon has been investigated. Substrate temperature T
s is increased to more than a critical temperature, and decreased to less than another critical temperature alternatively, and trisilane gas is injected as source molecules only in a short interval within the low-T
s phase. This method separates an adsorption phase of silicon hydrides with one-monolayer thickness from a desorption phase of hydrogen, resulting in the monolayer growth per cycle. ALE growth conditions were estimated from gas-source MBE characteristics, and ALE growth (with 0.8 monolayer/cycle) was demonstrated. The grown layer had good surface morphology and crystallinity.
Spatial Distribution of Trapped Holes in the Oxide of Metal Oxide Semiconductor Field-Effect Transistors after Uniform Hot-Hole Injection
Authors: Khosru Quazi Deen Mohd , Yasuda Naoki , Maruyama Akinori , Kenji Taniguchi Kenji Taniguchi , Chihiro Hamaguchi Chihiro Hamaguchi
Published: February 2005

Hole trap distribution and time dependence of the charge-free layer in the gate-oxide of p-channel metal oxide semiconductor (pMOS) transistors have been investigated after uniform hot-hole injection into the oxide of a set of pMOS transistors having very thin oxide thicknesses in the range of 4.6 to 10.6 nm. It has been found that the trap distribution has an exponential variation with respect to the distance from the Si/SiO2 interface and exists within 6 nm from the interface. A slight dependence of trapped-hole density on the oxide electric field was also found. A charge-free layer exists near the interface as a consequence of hole detrapping during relaxation. Measured time dependence of the charge-free layer during relaxation reveals that it increases initially with time and saturates at around 4 nm.
Monte Carlo Analysis of Hot Electron Transport and Impact Ionization in Silicon
Authors: Sano Nobuyuki , Masaaki Tomizawa Masaaki Tomizawa , Akira Yoshii Akira Yoshii
Published: February 2005

A novel impact ionization model which is consistent with a realistic band structure of Si has been developed. The present model contains only one parameter directly corresponding to the average matrix element for the ionization transition. The ionization probability is calculated at every k-point in the first Brillouin zone and the intrinsic anisotropy of the ionization probability is explicitly taken into account. Employing the Monte Carlo procedure including the present ionization model, the ionization coefficients are calculated and a best-fitting to the experimental ionization coefficients is obtained when the value of the parameter in the ionization model is equal to that extracted from the first-principles calculations.
Coupled Monte Carlo-Energy Relaxation Analysis of Hot Carrier Light Emission in Metal Oxide Semiconductor Field Effect Transistors's
Authors: Kurino Hiroyuki , Kiba Hiroyuki , Mori Hiroki , Yokoyama Shin , Yamaguchi Ken , Mitsumasa Koyanagi Mitsumasa Koyanagi
Published: February 2005

A new two-dimensional device simulator to analyze hot carrier photon emission has been developed. A new calculation algorithm of coupled Monte Carlo energy relaxation analysis is employed to obtain the carrier temperature distribution and the carrier energy distribution function at a fast computation turn around time. The relation between the hot carrier energy and the photon emission characteristics is easily obtained by using this simulator. The simulated results show excellent agreement with the experimental results. It is found from the comparison between the simulated and experimental results that the hot carrier energy distribution function is not described by the Maxwell-Boltzmann distribution.
Tunnel Structured Stacked Capacitor Cell (TSSC) with High Reliability for 64 Mbit dRAMs and Formation of Oxide-Nitride-Oxide Film (ONO) on 3-dimensionally (3d) Storage Electrode
Authors: Matsuo Naoto , Nakata Yoshiro , Ogawa Hisashi , Yabu Toshiki , Matsumoto Susumu , Masaru Sasago Masaru Sasago , Shozo Okada Shozo Okada
Published: February 2005

We developed a new 3-dimensionally(3d) stacked capacitor structure, a tunnel structured stacked capacitor cell (TSSC), for 64Mbit dRAMs. The TSSC with 2 tunnels realized improved reliability the same as that of the conventional stacked capacitor (STC) and a capacitance of 29 fF with a capacitor height of 0.25 µm because of side-wall electrode formation. The equivalent thickness of SiO2 for the oxide nitride oxide (ONO) is 7.8 nm, and the cell area is 1.8 µm2. The uniformity of the ONO inside the tunnel of the TSSC was confirmed except for the corner of the tunnel, while the thickness of the ONO is slightly greater at the corner. At the corner, the top oxide film of the ONO is slightly thicker than that at the other areas, and accordingly, the shape of the plate electrode at the corner becomes round. These shape effects lead to no generation of the local field concentration at the corner inside the tunnel. They are applied to the other 3d stacked capacitors which have generally been proposed.
Analytical Device Model of SOI MOSFETs Including Self-Heating Effect
Authors: Yasuda Naoki , Ueno Shuichi , Taniguchi Kenji , Hamaguchi Chihiro , Yamaguchi Yasuo , Nishimura Tadashi
Published: February 2005

A simple analytical model for device characteristics of silicon-on-insulator (SOI) MOSFETs is proposed. The effect of the self-heating is incorporated into a pseudo-2-dimensional drain-current model through an analytical expression using a thermal distribution-constant circuit. The device characteristics calculated with the model were found to agree well with experimental drain-current characteristics.
Single-Crystal Growth of Al(110) on Vicinal Si(100) in Ultra-High-Vacuum Sputtering System
Authors: Okamoto Shin Yokoyama
Published: February 2005

A single-crystal Al(110) film has, for the first time, been grown on a misoriented (100) Si substrate (4°off toward [011] direction) by using an ultra-high-vacuum sputtering system at 350°C without any additional high-temperature treatment. The growth mechanism of the single crystal on the vicinal Si surface is discussed based on our new model, in which the atomic steps play an important role.
High-Mobility Bottom-Gate Thin-Film Transistors with Laser-Crystallized and Hydrogen-Radical-Annealed Polysilicon Films
Authors: Shimizu Kazuhiro , Hosoya Hideki , Osamu Sugiura Osamu Sugiura , Masakiyo Matsumura Masakiyo Matsumura
Published: February 2005

High-performance bottom-gate thin-film transistors (TFTs) have been realized with excimer-laser-crystallized polysilicon films, for the first time. TFT characteristics were greatly dependent on the silicon film thickness as well as the pulsed-laser energy density. It was found also that posthydrogenation based on hydrogen-radical annealing improves the TFT characteristics drastically. The field-effect mobilities exceeded 220 cm2/Vs for electrons and 140 cm2/Vs for holes, respectively.
Low-Temperature Operation of Polycrystalline Silicon Thin-Film Transistors
Authors: Mori Hiroki , Hata Kiyomi , Hashimoto Takeshi , Wu I-Wei , Lewis Alan G. , Mitsumasa Koyanagi Mitsumasa Koyanagi
Published: February 2005

The influences of the grain boundary traps on poly-Si TFT (thin-film transistor) device characteristics were evaluated in detail by examining the low-temperature device characteristics. It was found that the absolute value of threshold voltage significantly increases and the field-effect mobility considerably decreases at low temperature because the influences of the grain boundary traps become more pronounced. As a result, the drain current is strikingly reduced specifically in n-channel TFTs when the temperature is decreased. Meanwhile, the kink effect is suppressed at low temperature due to the increased influences of the grain boundary traps. The hydrogenation treatment mitigated the drain current reduction at low temperature and enhanced the kink effect.
Threshold Voltage Shift of Amorphous Silicon Thin-Film Transistors During Pulse Operation
Authors: Oritsuki Ryoji , Horii Toshikazu , Sasano Akira , Tsutsui Ken , Koizumi Toshiko , Kaneko Yoshiyuki , Tsukada Toshihisa
Published: February 2005

The threshold voltage shift of amorphous silicon thin film transistors (TFT's) under pulse operation is discussed. The stress time, stress voltage, duty ratio and frequency dependence of the shift have been measured. A positive voltage stress causes a constant shift, when the frequency is in the range from DC to over 100 kHz. On the other hand, the shift under a negative pulse stress depends on its repetition frequency and its pulse width and can be described by an equivalent circuit model. Based on these data, a more reliable estimate of the long-term reliability of an amorphous silicon TFT panel has been realized.
TFT and Physical Properties of Poly-Crystalline Silicon Prepared by Very Low Pressure Chemical Vapour Deposition (VLPCVD)
Authors: Miyasaka Mitsutoshi , Nakazawa Takashi , Ichio Yudasaka Ichio Yudasaka , Hiroyuki Ohshima Hiroyuki Ohshima
Published: February 2005

This paper investigates the role of silane partial pressure (P
SiH
4) in VLPCVD on the as-deposited poly-Si film quality. The film quality strongly depends on the P
SiH
4 when deposition temperature is kept constant. Higher pressure and excessively lower pressure have been found to be not adequate for thin film transistors (TFTs). By optimizing the deposition conditions, excellent TFTs can be fabricated through a low temperature process without relying on any other special processes. This paper also suggests the possibility of further improvement of as-deposited poly-Si films.
Amorphous-Se/GaAs –A Novel Heterostructure for Solid-State Devices–
Authors: Takatani Shinichiro , Takeshi Kikawa Takeshi Kikawa , Masatoshi Nakazawa Masatoshi Nakazawa
Published: February 2005

Interface properties of an amorphous (a-)Se/GaAs(001) heterostructure made on a Se-stabilized (2×1) GaAs surface are investigated. Photoemission spectroscopy analysis shows that the band alignment is staggered with the valence band discontinuity of -0.27±0.05 eV. Amorphous-Se/GaAs diode current-voltage characteristics also support the staggered alignment. This is suitable for applications to photoelectric devices in which photogenerated holes in GaAs are injected into a-Se for low-noise avalanche multiplication. Capacitance-voltage characteristics of the diode show the presence of interface states near the conduction band edge of GaAs, in agreement with the Fermi-level position measured from photoemission spectroscopy. These pinning states are introduced through the deposition of a-Se, and may be attributed to outdiffused Ga atoms in a-Se.
1.5 µm-Long-Wavelength Multiple Quantum Well Laser on a Si Substrate
Authors: Sugo Mitsuru , Mori Hidefumi , Itoh Yoshio , Yoshihisa Sakai Yoshihisa Sakai , Masami Tachikawa Masami Tachikawa
Published: February 2005

Room-temperature cw operation of an InGaAs/InGaAsP multiple quantum well (MQW) laser diode on a Si substrate is reported. The MQW laser emits at 1.54-µm wavelength and exhibits no degradation after over 1,000 hours of operation. Employing a hybrid organometallic vapor-phase epitaxy/vapor mixing epitaxy method and a layer structure for improving crystalline quality, high-quality MQW were obtained. The stable longitudinal mode spectrum demonstrates the effectiveness of the MQW active layer and results in low-intensity noise. Annealing phenomena under cw operation are also discussed.
Molecular Beam Epitaxy Growth of AlGaAs/GaAs Vertical Cavity Surface Emitting Lasers and the Performance of PIN Photodetector/Vertical Cavity Surface Emitting Laser Integrated Structures
Authors: Wang Y. H. , Hasnain G. , Tai K. , Wynn J. D. , Weir B. E. , Choquette K. D. , Cho A. Y.
Published: February 2005

An all-epitaxial planar top emitting AlGaAs/GaAs multi-quantum well laser is fabricated and characterized. The constructed vertical cavity surface emitting laser (VCSEL) consists of GaAs/Al0.2Ga0.8As (100/80 Å) quantum wells sandwiched between two doped distributed Bragg reflectors characterized by a two-step composition profile. Two Ga and two Al cells are used to facilitate the growth of mirror profile. The gain-guided VCSEL is found to generate continuous wave at a characteristic temperature of 210°K up to 90°C, and can be amplitude modulated at frequencies above 5 GHz. Thresholds as low as 2 mA, and a CW power more than 1.5 mW, are obtained at room temperature.
Monolithic integration of a PIN photodetector on top of the VCSEL is demonstrated and discussed. The integrated photodetector shows an effective linear responsivity to the laser emission of 0.25 A/W.
Microwave Heterodyne Mixing by Step-Edge Microbridge Josephson Junctions Using YBaCuO Thin Films
Authors: Fukumoto Yoshito , Kajikawa Hiroshi , Rikuo Ogawa Rikuo Ogawa , Yoshio Kawate Yoshio Kawate
Published: February 2005

Current-voltage characteristics and microwave mixing properties of step-edge microbridge Josephson junctions (SEJJs) made of YBaCuO thin films were systematically investigated. The step-edge was formed on the surface of a MgO(100) substrate employing the common photolithograph and wet-etching techniques. YBaCuO thin film was deposited by the off-axis sputtering method, and the microbridge junctions were fabricated so as to cross the step-edge. The SEJJs showed typical DC and AC characteristics which were explained by the resistively shunted junction (RSJ) model. Mixing experiments were carried out in the K-band microwave region. An intermediate frequency (IF) output with the frequency range of 20 MHz∼2.0 GHz was successfully obtained.
Transient Rapid Thermal Annealing of Low-Dose High-Energy Phosphorus Implanted Silicon
Authors: Bársony István , Heideman Jean-Luc , Middelhoek Jos Klappe
Published: February 2005

A novel low thermal budget post-implantation annealing technique, the transient RTA (T-RTA) is proposed for low-dose high-energy P-implanted silicon wafers. Results with this short time (t
eff=300 ms) annealing on 3′′ substrates proved to be superior to conventional furnace anneal performance. Spreading Resistance carrier profiling and High Resolution X-ray Diffraction measurements indicated full dopant activation, minimum profile motion and complete damage removal. According to minority carrier lifetime profiling results, generation rates below 0.3 mA/cm3 could be achieved in the region of interest for device applications. Inhomogeneity of the sheet resistivity due to transient temperature gradients across the wafer remained below 2%, which is comparable or lower than those of furnace annealed samples.
High Quality Molecular Beam Epitaxial Regrowth of ZnSe on Se-Modified (100) GaAs Surfaces
Authors: Turco-Sandroff F. S. , Sandroff C. J. , T. S. Ravi T. S. Ravi , D. M. Hwang D. M. Hwang
Published: February 2005

We show that high quality MBE regrowth of ZnSe can be achieved on (100) GaAs surfaces that have been passivated outside the regrowth chamber with aqueous selenides. Good epitaxial regrowth of ZnSe on these Se-modified GaAs surfaces could be seen by reflection high energy electron diffraction and lattice images obtained by transmission electron microscopy reveal GaAs/ZnSe interfaces free of structural defects. We also show that these regrown interfaces are of high electronic quality with photoluminescence intensity measurements. The relatively low regrowth temperatures (270 and 350°C) combined with the wide band gap of ZnSe should make our scheme attractive for regrowth on many GaAs-based devices.
Reduction of Point Defects in GaAs Films Grown on Fluoride/Si Structures by the 2-Step Growth Method
Authors: Ono Atsuki , Tsutsui Kazuo , Osamu Ishiyama Osamu Ishiyama , Seijiro Furukawa Seijiro Furukawa
Published: February 2005

The reason why electrical characteristics of GaAs films grown on CaF2/Si(111) structures at high substrate temperature (600°C) are degraded is studied. Rutherford backscattering spectroscopy (RBS) measurements and secondary ion mass spectroscopy (SIMS) observations revealed that the degradation was due to point defects which resulted from a degraded interface region formed by mutual diffusion between GaAs and CaF2. It was found that the 2-step growth method was effective in reducing the point defects of GaAs film.
Gas Source MBE Growth of GaAs/AlGaAs Heterojunction Bipolar Transistor with a Carbon Doped Base Using Only Gaseous Sources
Authors: Sandhu Adarsh , Fujii Toshio , Ando Hideyasu , Takahashi Tsuyoshi , Ishikawa Hideaki , Naoya Okamoto Naoya Okamoto , Naoki Yokoyama Naoki Yokoyama
Published: February 2005

We report on the first growth of a GaAs/Al0.2Ga0.8As heterojunction bipolar transistor by gas source MBE using only gaseous sources. The p-type GaAs base layer was carbon doped using trimethylgallium (p=4×1019 cm-3) and the n-type Al0.2Ga0.8As emitter layer was silicon doped (n=9×1017 cm-3) using uncracked disilane. A dc current gain of 40 was obtained at a current density of 50 A/cm2.
Suppression of Diamagnetic Susceptibility in Extremely Thin Cylindrical Superconductor
Authors: Nagata Shoichi , Kinoshita Yasuhiro , Shuji Ebisu Shuji Ebisu , Susumu Chikazawa Susumu Chikazawa
Published: February 2005

Diamagnetic susceptibility χ has been calculated systematically on the basis of a simple London model with a special emphasis on extremely thin circular cylinders. Numerical solutions of χ are obtained as a function of a/λ; here a is the radius of the cylinder and λ is the London penetration depth. For smaller a, the magnetic flux will penetrate uniformly, and consequently, the Meissner effect is substantially smeared out.
A Boundary Oxidation Model for Amorphous Rare Earth-Transition Metal Films
Authors: Yumi Mizusawa Yumi Mizusawa , Katsutarou Ichihara Katsutarou Ichihara
Published: February 2005

Transmission electron microscopy and electron diffraction analysis of amorphous rare earth-transition metal alloy (RE-TM) films have been carried out to clarify the origin of experimentally obtained thickness dependence of their magnetic properties. It has been clarified that there is no islandlike structure even in a 5-nm-thick sample. It has also been clarified that there are an RE-oxide phase and a TM phase in samples with a thickness of below 10 nm. A boundary oxidation model for RE-TM films is proposed. The thickness of the boundary oxidation region (d
B) and magnetization excluding the influence of the boundary oxidation region (M
s
0) have been calculated based on this model. For films with an RE content of 27-28 at.%, the d
B values were 10 to 20 nm, and the M
s
0 values were 272 to 300 emu/cm3, which were 17% to 35% higher than the measured M
s values of 100-nm-thick films.
Reliability of 780-nm High-Power Laser Diodes with Thin Quantum Well Active Layer
Authors: Nakatsuka Shin'ichi , Yamashita Sigeo , Kenji Uchida Kenji Uchida , Takashi Kajimura Takashi Kajimura
Published: February 2005

The reliability of 780-nm-(AlGa)As high-power laser diodes with a thin triple-quantum-well or a single-quantum-well active layer is investigated. The thin active layers achieve high catastrophic optical damage levels above 170 mW. In these laser diodes, a gradual increase of the operation current limits the lifetime of the laser diode. The gradual degradation rate is higher in the single-quantum-well laser diodes than to the triple-quantum-well laser diodes, and is also higher in shorter-cavity-length laser diodes. The power dependence of the gradual degradation rate is very small compared with the dependence on cavity length or active layer structure. The gradual degradation mainly depends on the threshold current density per active layer thickness. As a result, 60-mW reliable operation for more than 1000 hours was achieved at 50°C in 600-µm-length triple-quantum-well lasers.
Chlorine-Kβ X-Ray Emission Band and Valence-Band Structure of AgCl
Authors: Chikara Sugiura Chikara Sugiura
Published: February 2005

The chlorine-Kβ emission spectrum in fluorescence from AgCl is measured with a high-resolution two-crystal vacuum spectrometer. The high-resolution spectrum consists of two separate peaks and is compared with the partial p density of valence states for AgCl obtained by Tejeda et al. There is a good agreement between them. The spectrum is compared with the chlorine-Kβ emission spectrum of CuCl, reported previously. There is a great difference between them.
Solid-State Phase Transformation in Cubic Silicon Carbide
Authors: Woo Sik Yoo Woo Sik Yoo , Hiroyuki Matsunami Hiroyuki Matsunami
Published: February 2005

The thermal stability of single crystalline 3C-SiC was investigated at temperatures from 1800 to 2400°C in an Ar atmosphere, and a solid-state phase transformation from 3C-SiC to 6H-SiC was observed above 2150°C. Single crystals of 3C-SiC(100) grown on Si(100) were used as starting crystals after removing Si. Annealings were carried out with changing temperature, pressure and time. The change in the Si/C composition ratio of annealed samples was determined by Auger electron analysis. The polytypes of samples were examined by photoluminescence, Raman scattering, X-ray diffraction and reflection high-energy electron diffraction before and after annealing. The spatial distribution and depth profile of the phase-transformed 6H-SiC region in annealed samples were observed by means of Raman microscopy. The mechanism of 3C→6H phase transformation in SiC is discussed.
Simulation of Rotating Magnetic Field Current Drive Using Multilayer Model
Authors: Lin Jing , Tajima Akio , Mitsuaki Suzuki Mitsuaki Suzuki , Eiki Hotta Eiki Hotta
Published: February 2005

Using a multilayer model of an infinitely long cylindrical plasma, the penetration of a transverse rotating magnetic field (RMF) into plasma has been investigated. The simulation shows that the transverse magnetic field can penetrate into plasma under certain conditions. The penetration is found to strongly depend on a quantity, R
3, which is the square of the ratio of the cross-sectional area of the plasma column to the skin depth. The critical condition for the RMF to penetrate into the plasma is obtained. The time evolution of axial magnetic field B

z
} distributions is simulated, and the B

z
distribution in steady state is found to coincide with that of the experimental result.
Formation of “bcc Boundary Phase” in Transmission Electron Microscopy Samples of Nd-Fe-B Sintered Magnets
Authors: Tsubokawa Yoshiyuki , Hirosawa Satoshi , Ryuichi Shimizu Ryuichi Shimizu
Published: February 2005

The microstructure of grain boundaries in Nd-Fe-B sintered magnets has been investigated by means of high-resolution transmission electron microscopy (HRTEM) in order to clarify the appearance of the “bcc grain boundary phase” reported earlier. No phase with bcc structure in TEM samples prepared by ion thinning in high vacuum has been observed but an amorphous like phase without bcc structure formed on both surfaces of a TEM sample during ion bombardment for thinning. Heating of the samples under the presence of oxygen induces the precipitates of bcc microcrystals in the amorphous like phase. This clearly suggests that the “bcc boundary phase” is formed through the preparation procedure of TEM samples.
Intensity Profiling of an Unattenuated, Focused High Power cw Argon-Ion Laser Beam
Authors: G. J. Willems G. J. Willems , H. E. Maes H. E. Maes
Published: February 2005

In this paper a high resolution laser beam intensity profiler is proposed which is capable of profiling focused high power cw Ar+-laser beams without any prior attenuation of the laser beam. The profiler makes use of a pinhole scanned across the laser spot to be measured. The method of extraction of the parameters which characterize the intensity profile of the laser spot, such as spot size and higher-order Transversal Electromagnetic (TEM) mode content, is discussed. Finally some applications of the high resolution intensity profiler are treated.
MOS-Type One-Dimensional Position-Sensitive Detectors with a Linearly Detectable Face of 30 mm Long
Authors: Matsubara Yoshihiro , Kodai Toshiya , Yoshida Haruhiko , Niu Hirohiko , Tetsuro Matsuda Tetsuro Matsuda , Seigô Kishino Seigô Kishino
Published: February 2005

Experiments have been conducted for the MOS-type position-sensitive detector (PSD) to make one-dimensional PSDs of large detection range, based on the previous theoretical suggestion that the MOS-type PSD under some conditions linearly detects a light-spot position in the full range of its detectable face. The almost perfect linearity and also fine resolution higher than 1 µm have been demonstrated for an Al-SiO2-Si one-dimensional PSD with a detectable face of 30 mm long.
Heterodyne Detection of Microwaves Using Granular-Type Y1Ba2Cu3O7-x Superconductors
Authors: Yoshisato Yorinobu , Takeoka Akio , Takai Minoru , Niki Kazuya , Yoshikawa Shuichi , Toshimasa Hirano Toshimasa Hirano , Shoichi Nakano Shoichi Nakano
Published: February 2005

A heterodyne mixing experiment of microwaves at about 20 GHz was performed using a microwave detector made from granular-type Y1Ba2Cu3O7-x
(YBCO) superconductors. Although the bridge included many boundaries, voltage steps corresponding to the Josephson frequency and step height dependence for microwave power similar to those of a single weak-link bridge were clearly observed. The IF signal showed peak amplitudes corresponding to the peak dynamic resistantance due to nonlinearity resulting from the Josephson effect. It was confirmed for the first time that this detector operates stably for the heterodyne mixer at 60 K or below and has a potential for high sensitivity due to its large dynamic resistance.
A Monochromatic Black and White Supertwisted Nematic Liquid Crystal Display with a Single Cell and a Birefringent Film
Authors: Hirakata Jun-ichi , Komura Shin-ichi , Nagae Yoshiharu , Kaneko Eiji , Kinugawa Kiyoshige , Kando Yasuhiko , Kawakami Hideaki
Published: February 2005

To achieve a monochromatic black-and-white (B/W) STN-LCD with a single cell and a birefringent plastic film, the optimum conditions of optical properties in the birefringent film are analyzed theoretically and experimentally. By optimizing the film retardation to minimize the transmission of a STN-LCD at 550 nm, optical retardation in a STN cell is canceled and a B/W STN-LCD is obtained. By selecting the suitable conditions for compensating retardation of the STN cell, a B/W STN-LCD is achieved with the contrast ratio of 10:1.
Atomic Structure Analysis of Amorphous Tb-Fe1-xCoxFilm Systems
Authors: Kato Yoshimine , Takayama Shinji , Matsubara Eiichiro , Waseda Yoshio
Published: February 2005

The atomic structure of sputtered amorphous Tb-Fe1-xCoxthin film systems was studied by X-ray scattering. The composition fractionxwas varied systematically, and the basic atomic structures of Tb-Fe1-xCoxfilms were similar as a whole. The interatomic distances in Tb-Fe1-xCoxfilms annealed at 200°C, overall, tend to decrease when the Co content is increased. These distances seem to change discontinuously at a composition of aroundx=0.5. The coordination numbers of the corresponding atoms did not show much correlation with Co concentration except in the case of transition metal atoms around a transition metal atom. In this case, the coordination number increases after annealing, but this increment tends to decrease as the Co concentration increases in Tb-Fe1-xCoxfilms.
Al, Cu and W Oxide Fine Particles Produced by Discharge Explosions
Authors: Sahashi Toshio , Yamada Yoshiaki Hioki
Published: February 2005

When a large current produced by the discharge of a charged capacitor is introduced to Al, Cu and W wires in air, it evaporates the wires explosively, and metal oxide fine particles are thus produced. The resulting fine particles are γAl2O3, Cu2O and WO3, and their average diameters are 200, 200 and 100 Å, respectively. Comparison of smoke balls produced by the discharge-explosion method (DEM) and those produced by the conventional gas-evaporation method (CGEM) shows that the size of the smoke balls produced by the DEM was ten times or more greater than that of smoke balls produced by the CGEM. In terms of the diameters of particles, the size produced by the DEM was, at most, one-tenth that produced by the CGEM.
Effect of Ar Gas Addition on AlN Film Formation by Microwave Plasma Chemical Vapor Deposition
Authors: Someno Yoshihiro , Makoto Sasaki Makoto Sasaki , Toshio Hirai Toshio Hirai
Published: February 2005

AlN films were prepared on Si(100) substrates by coaxial-line type microwave plasma chemical vapor deposition (CVD) using an AlBr3-H2-N2-Ar gas system. Effects of the Ar gas flow rate on the film structure, crystallinity and deposition rate were investigated under the deposition conditions of an AlBr3 flow rate of 1.37 10-4 mol·min-1, N2/AlBr3 molar ratio of 16, microwave power of 700 W, and total gas pressure of 53.2 Pa. The deposition rate increased with increasing Ar gas flow ratio in the range of 36 to 66%. Strong c-axis oriented AIN film was obtained at a lower substrate temperature of 380°C and at Ar gas flow ratio of 66%. In-situ plasma-emission spectra during deposition showed an increase in the Al, AlBr radical and N2
+ ion-emission spectra intensity with an increase in deposition rate resulting from the increase of Ar gas flow rate. This result suggests that auxiliary Ar gas promotes plasma-radical dissociation.
Atomic Structure of CaF2/Si(111) Interface and Defect Formation on CaF2(111) Surface by Electron Irradiation
Authors: Miura Kouji , Sugiura Kazuhiko , Souda Ryutaro , Aizawa Takashi , Oshima Chuhei , Ishizawa Yoshio
Published: February 2005

Atomic and electronic structures of the CaF2/Si(111) interface and the desorption mechanism of F from epitaxial CaF2(111) films produced by electron irradiation have been studied by low-energy ion scattering spectroscopy (ISS) and low-energy electron energy loss spectroscopy (EELS). The interface is formed by the desorption of F and becomes metallic. The F at the surface of epitaxial CaF2(111) films desorbs by electron irradiation, and the surface after F-desorption becomes metallic. The metallic surface reverts to the bulk electronic state before electron irradiation by annealing at about 400°C.
Electric Field Effects in Parabolic Quantum Wells
Authors: C. Juang C. Juang
Published: February 2005

Within the framework of the effective mass approximation, a theoretical study of energy level shift and field-induced tunneling in parabolic quantum wells is presented. Energy level shifts in infinite and finite parabolic quantum wells are calculated from the time-independent Schrödinger equation using the inverse power method, incorporating the position-dependence of the effective mass. The time evolution of an electron wavepackage is shown by the application of the time-development operator according to the time-dependent Schrödinger equation. Tunneling probability and tunneling lifetime in parabolic quantum wells based on the time-dependent Schrödinger operator are evaluated versus applied field.
Pitch-Angle Measurement of Ions by the Use of a Small Faraday Cup
Authors: Ichimura Makoto , Inutake Masaaki , Asari Eiji , Adachi Satoshi , Katsumata Ryota , Yoichi Kimura Yoichi Kimura , Syoichi Miyoshi Syoichi Miyoshi
Published: February 2005

The pitch-angle distribution of ions in the ICRF-heated plasma is measured using a small Faraday cup in the central cell of a GAMMA 10 tandem mirror. The pitch-angle distribution in the slow wave heating experiment shows the turning points of the mirror-trapped ion center into the ion cyclotron resonance layer. The temperature anisotropy defined by T
⊥/T
// is evaluated when the resonance layer is located near the midplane in the central cell of the GAMMA 10 tandem mirror.
Breakdown of the Mixture (Ar/SF6) in a Needle-Plane Gap under µs Pulse Voltage
Authors: Nakayama Hiroshi , Onoda Mitsuyoshi , Yasuhiro Sumino Yasuhiro Sumino , Kiyoshi Amakawa Kiyoshi Amakawa
Published: February 2005

The V-t curves of the corona and breakdown in a needle-plane gap of a mixture (Ar/SF6) were investigated in both polarities under pulses with various rise times. The V-t curve of the mixture (SF6/Ar) changed from a monotonous decreasing pattern to an inverse “V” pattern with increasing admixture of SF6 in positive polarity. The latter pattern was abnormal; that is, the breakdown voltage increased to a maximum and then decreased with increasing rise time. This abnormal V-t curve was also obtained with a smaller amount of admixture of SF6 to Ar under negative polarity