Photoinduced structural changes in obliquely deposited As- and Ge-based amorphous chalcogenides: correlation between changes in thickness and band gap

The effect of band gap illumination and annealing below the glass transition temperature on the thickness and the optical band gap of As-based (As2Se3, As2S3) and Ge-based (GeSe2, GeS2) obliquely deposited chalcogenide films has been studied. It is observed that in the case of arsenic (As)-based glasses, illumination increases the thickness (expansion) and the band gap decreases (darkening), while as for germanium (Ge)-based glasses, both thickness and band gap show an opposite behavior to that of As-based glasses. By annealing the samples, before and/or after illumination, the trends of the changes in thickness and band gap are reversed. A strong correlation between the changes in thickness and band gap has been established for the first time. (C) 1998 Elsevier Science B.V. All rights reserved.