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Atomic layer epitaxy of cubic SiC was investigated to examine gas reaction on the surface at high temperature using Auger electron spectroscopy and low energy electron diffraction. Self-limiting growth at one and one-third atomic monolayers at 1050°C was observed for exposure of a carbon-terminated surface to Si2H6, and self-limiting growth at just one atomic monolayer was observed for exposure of a silicon-saturated surface to C2H2. It was also found that the extra partial silicon layer of the silicon-saturated surface desorbs during C2H2 exposure. By alternating exposure to Si2H6 and C2H2, accurate layer-by-layer growth is achieved. In this system, the spontaneous atomic layer desorption of silicon which occurs during C2H2 exposure is consistent with the nature of exact atomic layer epitaxy.

We have prepared yttrium barium copper oxide superconducting thin films on MgO(100) substrates by newly developed metalorganic molecular beam epitaxy. As source materials, we have used fluorine-free β-diketonate chelates of yttrium, barium and copper. The films annealed at 940°C had the c axis oriented normal to the substrate surface and exhibited superconducting properties with Tc (zero resistance) = 45 K.

We have grown BiSrCaCuO superconducting films on MgO(100) substrates by metalorgic chemical vapour deposition (MOCVD) using triphenyl bismuth and β-diketonates of strontium, calcium and copper as source materials and studied the thickness and growth rate dependences of the zero-resistance temperature Tc(0). We have obtained a film showing Tc(0) = 95 K without postannealing, which is the highest Tc(0) among as-deposited films by MOCVD reported so far.

Etude, dans le cas de films obtenus par epitaxie par faisceaux moleculaires, de l'influence du chauffage a l'air du substrat GaAs, dope par Cr-O, durant le processus de montage, sur la structure du substrat, les impuretes de la surface et les proprietes de luminescence d'un film GaAs sur le substrat

Single-crystal films of AlN were fabricated on sapphire (0001) substrates by the reactive evaporation of aluminium in NH3 gas at 1050 °C. The cathodoluminescence spectra of AlN films doped with twenty different elements including manganese, copper, magnesium, niobium and zinc and of undoped films were measured in the wavelength region 250–900 nm at room temperature. The films doped with manganese and niobium show peaks at about 595 and 510 nm whereas the spectra of the films doped with zinc, copper and magnesium using partially ionized beams have peaks or shoulders at about 420 and 460 nm (these wavelengths do not depend on the species of the doping atoms) in addition to the peak at 370 nm observed for undoped films. The results are discussed in conjunction with those observed for single-crystal AlN slabs and AlN powder.

The optical effective mass of tin-doped In 2 O 3 films prepared by r.f. reactive sputtering has been determined from measurements of the plasma resonance frequency in the near-infrared region and the refractive index in the visible region. It is found that the optical effective mass changes from 0.31 m 0 to 0.43 m 0 when the carrier concentration is increased from 1.0 × 10 19 t0 8.2 × 10 20 cm -3 , where m 0 is the electron rest mass. With increase in the carrier concentration the shifts of the absorption edge due to the direct and to the indirect transition were measured in the near-ultraviolet region. The results are discussed in terms of the effective mass and the band structure of the In 2 O 3 crystal.