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

Abstract Photo-induced thickness changes in obliquely deposited amorphous As 2 S 3 and GeSe 2 films have been measured to determine the mechanisms of changes during illumination . For As 2 S 3 , the thickness increases and then decreases and saturates after some time. There is a decrease followed by saturated change even after the illumination is switched off. On the other hand, GeSe 2 has a continuous decrease of thickness with time, which remains constant after the illumination is turned off. The difference in these properties between As 2 S 3 and GeSe 2 films is discussed in terms of different structural units for these films (layered for a-As 2 S 3 and three-dimensional for a-GeSe 2 ).