Kohzo Sugiyama

Vapor deposition of thin cadmium sulfide layers using thermal decomposition of dithiolatocadmium complexes

Deposition process of CdS thin layers by pyrolysis of dimethyldithiophosphinatocadmium complex, [(CH3)2PS2]2Cd, is reported. The deposit obtained by the process is optically, electrically and chemically pure wurtzite-type cadmium sulfide. The substrate effect on the deposition rates and crystal orientation is observed and discussed.

Low temperature deposition of hexagonal BN films by chemical vapour deposition

Abstract Transparent hexagonal BN films were deposited onto copper substrates from the reactant gas BCl 3 -NH 3 -H 2 at temperatures in the range 250–700°C. The lowest deposition temperature of the films was about 250°C. The films deposited at temperatures below 450°C were unstable in moist atmosphere and devitrified; a 20%–30% decrease in weight was observed when these films were heated above 600°C in an argon atmosphere. In contrast, the films deposited at temperatures above 600°C were very stable, decreased in weight by 1%–2% on heating and were stable in air at temperatures below 750°C.

Chemical vapor growth of LaB6 whiskers and crystals having a sharp tip

Single crystals of LaB6 were grown from a gas mixture of LaCl3, BCl3, H2 and Ar on a graphite substrate at 1100–1300°C. Most of the crystals grew in the shape of pyramids or whiskers, however, square pyramidal crystals with the tip curvature of 0.01-0.1 μm were obtained at 1250°C. The crystal color changed from reddish-purple to blue as the BCl3 concentration was increased. Whiskers of 1–20 μm thick and 2–5 mm long were obtained at 1150°C after 1 h of growth. Some properties of the crystals were also examined and reported.

Low temperature deposition of a refractory aluminium compound by the thermal decomposition of aluminium dialkylamides

Abstract Aluminium dialkylamides decomposed at 300–500°C, 30–40 Torr in nitrogen or argon affording the deposits which were identified as aluminium nitride or carbonitride. They were hard and highly oxidation-protective.

Chemical vapor deposition of nickel phosphide Ni2P

Abstract Dinickel phosphide Ni2P was deposited from a gas mixture of NiCl2, PC13, H2 and Ar. A maximum deposition rate was obtained at 950 – 1000 °C and PCl3/NiCl3 − 1.1. The atomic ratio P/Ni in deposits increased with increasing PCl3/NiCl2 ratio in the input gas and attained a constant value (rP/Ni= 0.53) at gas ratios above 1.0. The average microhardness increased with increasing PCl3/NiCl2 ratio and attained a constant value (about 1000 kg mm−2) above a ratio of unity. Molybdenum plate coated with Ni-P compounds under various conditions was more resistant than nickel plate or electroless nickel-plated iron.

Chemical vapour deposition of TiO2 film using an organometallic process and its photoelectrochemical behaviour

Vapour pyrolysis of ethyl titanate has been performed in order to obtain thin TiO2 films. A selective deposition of rutile films is found to occur when substrate temperatures are below 500°C and the gas phase has a large linear velocity. The physical properties of the as-grown films, including their photoelectrochemical behaviour, are examined in relation to their condition of deposition. A thick rutile film grown on a Ti plate converts light energy to electricity with good quantum efficiency in a photoelectrochemical cell.

Chemical vapor growth of Cr5Si3 whiskers and hollow crystals

Abstract Whiskers and hollow crystals of Cr 5 Si 3 were grown on a silicon plate and on its holder from a gas mixture of chromium dichloride, hydrogen and argon in a temperature range of 950–1150°C.

Electrical and electrochemical properties of TiO2 films grown by organometallic chemical vapour deposition

The electrical and photoelectrochemical properties of TiO2 films, which were obtained by the vapour decomposition of ethyl titanate, are described. The electrical properties depend mainly on the deposition temperature. Films deposited at high temperatures have much lower electrical conductivity but remarkably higher photosensitivity than those deposited at low temperatures. The deposition temperatures are found to affect the electrochemical properties, such as anodic photocurrent–potential characteristics and spectra dependence of anodic photocurrents. Some doping effects of Al, Cr and Fe on the both properties are also examined.

Chemical vapour growth of CrB2 and CrB crystals

Abstract Crystals of CrB 2 and CrB were grown from a gaseous mixture of CrCl 2 , BCl 3 , H 2 and Ar in a temperature range of 1050–1100°C. Hexagonal planar crystals of CrB 2 grew to a size of 6 mm in diagonal and 0.1 mm in thickness at 1050°C for 2 h. Hollowed pillar crystals of CrB (1–10 μm thick and 30–100 μm long) grew on a platinum dispersed substrate at 1100°C. The growth mechanism of quasi-nonagonal pillars of CrB was supposed to be repeated twinning across the (110) planes. The composition of CrB 2 was confirmed by gravimetric analysis to be nearly stoichiometric. The microhardness of CrB 2 and CrB deposits was measured to be as 3800–4000 and 1450–1500 kg/mm 2 , respectively.

Chemical vapour deposition of tantalum diboride

Tantalum diboride (TaB2) was deposited on a quartz substrate from a gas mixture of TaCl5, BCl3, H2, and Ar at a temperature between 900 and 1300° C. When the atomic ratio (B/Ta) in source gas was held above 1.0 at 1000° C, TaB2 with a composition of between TaB1.90 and TaB1.95 was obtained in a single phase. The deposits grew to grain crystals with an increase in temperature and with an increase in the atomic ratio (B/Ta) in the source gas. The mass transfer of TaCl5 was supposed to be the rate-determining step. The Vickers microhardness values for the coating deposited at 1100° C from a source gas with atomic ratio (B/Ta) above 1.0 were 3500 to 4100 kg mm−2. Dispersing Ni or Pd on the substrate as an impurity, woolly crystals of up to 100μm in length were grown in 30 min at 1050° C, and the growth mechanism was thought to be that of tip-VLS.