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The effects of light irradiation on crystal growth were investigated in the vapor epitaxial growth of silicon. It was observed that the activation energy of crystal growth decreased with light irradiation. The magnitude of the decrease was 2.1 kcal/mole under the typical experimental condition in an r f heating reactor. Crystal growth was carried out at a temperature lower than that used in the conventional epitaxial method, and the crystal quality of the grown layers was found to be better in the case with light irradiation than that without irradiation. The above results suggest that light irradiation techniques can be used for reducing the degradation of impurity distribution by decreasing the growth temperature. At present, selective crystal growth according to an irradiation pattern can be realized. It is expected that epitaxial growth with light irradiation can be applied to a selective growth process.

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The etch rate of SiC crystals with hydrogen was investigated as a function of the reaction temperature, the hydrogen flow velocity and the hydrogen partial pressure in the H2-Ar mixture. An etching reaction mechanism and calculated expressions for the etch rate have been developed based on thermodynamical considerations. The experimental results are well explained from the approximate expression at the etch rate region higher than about 3 µ/min.

Characteristic changes occurring in SmBa 2 Cu 3 O y superconductors on substituting Sm for Ba have been investigated. An appropriate amount of Sm substitution (0.05 ≤ x ≤ 0.4, in the form of Sm 1+x Ba 2−x Cu 3 O y ) promoted grain growth; the grain size became larger than that in the non-substituted sample and had a maximum value at x = 0.07. Single-phase samples were obtained for 0 ≤ x ≤ 0.8. The critical temperature increased by about 1.5 K for concentrations up to x = 0.02, while it decreased rapidly beyond this amount. Samples did not show superconductivity above 15 K for x ≥ 0.4. The crystal structure transformed from orthorhombic to tetragonal at x = 0.3. The average valency of the Cu and the oxygen content decreased linearly with increase of x in the ranges of 0 ≤ x ≤ 0.3 and 0.7 ≤ x ≤ 0.8, while they both increased linearly for the range 0.3 ≤ x ≤ 0.7.