Showing papers by "Hiroshi Yamaguchi published in 1989"

Step-Flow Growth on Vicinal GaAs Surfaces by Migration-Enhanced Epitaxy

Abstract: The mechanism of step-flow growth on vicinal GaAs substrates during migration-enhanced epitaxy are studied using the reflection high-energy electron diffraction technique. Results show that the low As pressure during migration-enhanced epitaxy growth accelerates step-flow growth. In addition, it is also shown that monolayer terraces composed of surface Ga atoms are formed from step edges during the Ga deposition process. A GaAs/AlAs tilted superlattice is established using this growth technique. X-ray diffraction measurement and transmission electron microscopy observations show that the fabricated structure has periodic composition modulation along the axis tilted from the substrate azimuth.

Surface Migration of Ga and Al Atoms on (100) GaAs and AlAs during Migration-Enhanced Epitaxy

Abstract: Adsorption and migration characteristics of Ga and Al atoms on the GaAs and AlAs (100) surfaces are investigated using reflection high-energy electron diffraction along the alternate deposition of Ga or Al and As4 on the growing surface. Different characteristics are observed for Ga atoms deposited on a GaAs surface and for Al atoms deposited on an AlAs surface. Excess Ga deposition to the GaAs surface produces Ga clusters or droplets on the first Ga layer. They are dissolved very quickly after As4 deposition to form flat GaAs layers when the number of Ga atoms is closely equal to twice or three times the surface site number. This is not true, however, for Al deposition on AlAs. Different characteristics are also found for Ga and Al atoms deposited on the As-stable GaAs surface. All these results are interpreted in terms of different migration velocities of Ga and Al atoms.

Anomalous Distribution of In Atoms in GaAs during Migration-Enhanced Epitaxy

Abstract: An InAs monolayer is grown between GaAs layers using migration-enhanced epitaxy. The surface chemical characteristic during growth is investigated by reflection high energy electron diffraction. When the substrate temperature is about 500°C, the oscillation amplitude of reflected electron beam after growth of one monolayer of InAs vanishes during the growth of GaAs over more than 20 atomic layers. High-resolution secondary-ion mass spectroscopic analysis of the fabricated structures indicates that the anomalous distribution of In atoms with a gradual slope towards the growth direction occurs when the substrate temperature is 500°C. The experimental results are explained in terms of the replacement of In atoms in the InAs monolayer by the newly deposited Ga atoms.

[A case of immune-complex type glomerulonephritis associated with dermatomyositis].

Abstract: 患者は46才の女性.昭和59年頃に皮膚筋炎と診断され,プレドニゾロン30mg/日にて治療開始.昭和62年10月頃初めて蛋白尿が出現し,腎生検を施行.蛍光抗体法および電顕から糸球体基底膜にimmune-complexの沈着が認められたため,皮膚筋炎にimmune-complex型糸球体腎炎の合併が考えられた.皮膚筋炎に合併する糸球体病変は少ないとされ,本症例はまれな症例と考えられたため,文献的考察を加えて報告する.

Nonrepetitive Measurements of Wave and Plasma Parameters along a Low Frequency Surface Wave-Produced Plasma Column by an Interferometer Method

Abstract: An interferometer method for surface wave-produced plasma column study was developed into the nonrepetitive and simplest form. The principle was applied to the successive measurements of both wave and plasma parameter variations along a low frequency (28 MHz) surface wave-produced plasma column. The interferogram obtained by experiments could be used for the simplest point-determinations of the wave number, attenuation coefficient and plasma density variation along the plasma column. The electron-neutral collision frequency and the electron temperature were estimated from the wave attenuation.