Photo-induced selectivity of metal deposition on the surface of chalcogenide vitreous semiconductors

Abstract

A novel photo-induced phenomenon, namely a decrease in group II metal condensation rate on the surface of chalcogenide vitreous semiconductors (e.g. As₂S₃, As₂Se₃, As₁₅Se₈₅, GeS₂ and TlAsS₂) caused by previous irradiation by actinic light is reported. It is shown that the kinetics of metal deposition consist of two parts of which only the first is light sensitive. From a set of experiments the conclusion is drawn that metal deposition selectivity is caused by photo-oxidation of the semiconductor surface and by a change in its chemical composition due to illumination. In some cases a ‘negative’ effect can be observed when the metal is preferentially deposited on the illuminated regions of chalcogenide. It is shown that group II metal deposition selectivity is not unique to the amorphous state but can be observed on crystalline As₂S₃ as well. A model for the process is discussed.