In situ measurements of photo-induced volume changes in amorphous chalcogenide films

Photo-induced thickness changes in obliquely deposited amorphous As2S3 and GeSe2 films have been measured to determine the mechanisms of changes durin g illumination. For As2S3, the thickness increases and then decreases and s aturates after some time. There is a decrease followed by saturated change even after the illumination is switched off. On the other hand, GeSe2 has a continuous decrease of thickness with time, which remains constant after t he illumination is turned off. The difference in these properties between A s2S3 and GeSe2 films is discussed in terms of different structural units fo r these films (layered for a-As2S3 and three-dimensional for a-GeSe2). (C) 2000 Elsevier Science B.V. All rights reserved.