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UHV‐deposited amorphous silicon was recrystallized on (100) single‐crystal substrates using pulsed Nd : YAG laser irradiation. Prior to deposition, substrates were prepared with either atomically clean surfaces, residual argon ion sputter damage, or from one to three monolayers of residual oxide. Epitaxial regrowth of bulk crystalline quality occurred regardless of substrate preparation. Annealing energy densities were significantly higher, however, for substrates retaining residual impurities. Certain layers were doped with Ga. At moderate doping levels recrystallization behavior was unaffected. At a 2% doping level, the annealing energy threshold dropped by one‐half and Ga atoms were displaced toward the epitaxial surface. It is shown that the decrease in energy threshold is due to an impurity‐induced increase in light absorption within the amorphous layer. Layers were crystallized with substitutional Ga concentrations of up to 10 times the equilibrium solid solubility limit.

Parallel secondary electron and charge collection images of a CdS/Au Schottky barrier show that photoetching of the CdS improves the charge collection efficiency. This is explained in terms of preferential removal of (near) surface recombination centers by the photoetching. Evidence is given that lack of photoetching of specific areas of the surface is due to the fact that such areas are photoelectrochemically inactive, possibly because of poor electrical contact with underlying CdS, and combined photoetching and scanning electron microscopy investigation is suggested as a way to check semiconductors for inactive regions.

Pt‐Si alloy layers are formed during 130‐nsec pulsed irradiation of Pt coated Si with light from a Nd : YAG laser. The alloys form via surface melting and resolidifaction. Laser processing of arsenic of ion implanted, p‐type silicon results in formation of a p‐n+/Pt‐Si structure that exhibits rectifying electrical behavior. This structure arises because the As and Pt impurities are zone refined to different extents during resolidification of the molten surface layer.