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Hiroyuki Tachibana

Bio: Hiroyuki Tachibana is an academic researcher from Hiroshima University. The author has contributed to research in topics: Amorphous silicon & Chemical vapor deposition. The author has an hindex of 1, co-authored 2 publications receiving 114 citations.

Papers
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Journal ArticleDOI
TL;DR: Amorphous silicon (a•Si) films are deposited at about 320˚C by a new thermal chemical vapor deposition method as mentioned in this paper, where the gas mixture of intermediate species SiF2 and H2, decomposed thermally by the catalytic reaction, is used as a material gas.
Abstract: Amorphous silicon (a‐Si) films are deposited at about 320 °C by a new thermal chemical vapor deposition method. In this method, the gas mixture of intermediate species SiF2 and H2, decomposed thermally by the catalytic reaction, is used as a material gas. It is found that the photosensitivity of the a‐Si film for AM1 of 100 mW/cm2 exceeds over 106 and that the spin density is as low as 1.5×1016 cm−3 for the film deposited with a rate of several A/s.

114 citations

Journal ArticleDOI
TL;DR: In this article, a new Chemical Vapor Deposition (CVD) method to prepare high quality amorphous silicon (aSi) is presented, in which the gas mixture of intermediate species SiF 2 and atomic hydrogen, which is decomposed thermally by the catalytic reaction between H 2 gas and heated tungsten filaments, is used as deposition gases.
Abstract: A new Chemical Vapor Deposition (CVD) method to prepare high quality amorphous silicon (aSi) is presented. In the method, the gas mixture of intermediate species SiF 2 and atomic hydrogen, which is decomposed thermally by the catalytic reaction between H 2 gas and heated tungsten filaments, is used as deposition gases. It is found that the photo-sensitivity of the aSi film for AM-1 of 100 mW/cm 2 exceeds over 10 6 , the spin density of the film is as low as 6×10 15 spins/cm 3 and that the Staebler-Wronski effect is much weaker in the film than in the conventional aSi films.

1 citations


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TL;DR: It is demonstrated that during irradiation with high-energy heavy ions amorphous silicon deforms plastically in the same way as conventional glasses, providing experimental evidence for the existence of a low-density liquid.
Abstract: Amorphous silicon is a semiconductor with a lower density than the metallic silicon liquid. It is widely believed that the amorphous-liquid transition is a first-order melting transition. In contrast to this, recent computer simulations and the experimental observation of pressure-induced amorphization of nanoporous silicon have revived the idea of an underlying liquid-liquid phase transition implying the existence of a low-density liquid and its glass transition to the amorphous solid. Here we demonstrate that during irradiation with high-energy heavy ions amorphous silicon deforms plastically in the same way as conventional glasses. This behaviour provides experimental evidence for the existence of the low-density liquid. The glass transition temperature for a timescale of 10 picoseconds is estimated to be about 1,000 K. Our results support the idea of liquid polymorphism as a general phenomenon in tetrahedral networks.

138 citations

Journal ArticleDOI
TL;DR: In this paper, a new type of thermal chemical vapor deposition (CVD) method is presented, where material gases are decomposed by catalytic or pyrolytic reaction with a heated catalyzer, so that films can be deposited at temperatures less than 300°C without any plasma or photochemical excitation.
Abstract: A new type of thermal chemical vapor deposition (CVD) method is presented. In the method, material gases are decomposed by catalytic or pyrolytic reaction with a heated catalyzer, so that films can be deposited at temperatures less than 300 °C without any plasma or photochemical excitation, and the method is particularly called ‘‘Catalytic‐CVD.’’ Hydrogenated amorphous silicon films are deposited by this method, and the deposition mechanism is also investigated. It is found that device‐quality amorphous silicon films can be obtained and that inactive species, which are generated at the catalyzer and transported without gas‐phase reactions, are key species to make a high‐quality film by this method.

125 citations

Journal ArticleDOI
TL;DR: In this article, an air-stable n-type carbon nanotube field effect transistors (CNTFETs) were fabricated with Si3N4 passivation films formed by catalytic chemical vapor deposition (Cat-CVD).
Abstract: Air-stable n-type carbon nanotube field-effect transistors (CNTFETs) were fabricated, with Si3N4 passivation films formed by catalytic chemical vapor deposition (Cat-CVD). Electrical measurements reveal that the p-type characteristics of CNTFETs are converted to n-type after fabricating Si3N4 passivation films at 270°C. This indicates that adsorbed oxygen on the CNT sidewalls was removed during the formation process of the Si3N4 passivation films. In addition, the source-drain current of the n-type CNTFETs does not change over time under vacuum, or in air. Consequently, the n-type CNTFETs are completely protected by the Si3N4 passivation film from further effects of ambient gases. Therefore, Cat-CVD is one of the best candidates to fabricate Si3N4 passivation films on CNTFETs.

95 citations

Journal ArticleDOI
TL;DR: In this paper, the recent progress in the catalytic chemical vapor deposition (Cat-CVD) research project, supported by the New Energy and Industrial Technology Development Organization (NEDO), is reviewed.

84 citations

Journal ArticleDOI
TL;DR: In this article, a method for crystallizing amorphous silicon (a-Si) films at low temperatures was proposed, where the hydrogen atoms were generated by catalytic cracking reaction of H2 gas on a heated tungsten catalyzer in the catalytic chemical vapor deposition apparatus.
Abstract: A method for crystallizing amorphous silicon (a-Si) films at low temperatures is proposed. In the method, a-Si films are crystallized at temperatures lower than 400 °C by annealing in the presence of atomic hydrogen. The hydrogen atoms are generated by catalytic cracking reaction of H2 gas on a heated tungsten catalyzer in the catalytic chemical vapor deposition apparatus. It is found that the crystalline fraction of such an a-Si film is increased from 0% to several tens %, and at the same time the a-Si film itself is etched with the rate of several tens nm/min by annealing in atomic hydrogen. This increment of crystalline fraction appears dependent on the quality of initial a-Si films. It is implied that there are several types of a-Si even if the difference among a-Si films cannot be detected by Raman scattering spectroscopy and other means for measurements.

70 citations