Photo-induced effects in Ge-As-Se films in various states

Abstract

Amorphous Ge-As-Se thin films have been prepared by the magnetron sputtering deposition technique, and the photo-induced effects (PIEs) in the different states have been investigated. It was found that, for the as-deposited films, Ge5 exhibits photodarkening (PD) while Ge15 and Ge25 undergo photobleaching (PB), and the degree of PB in Ge25 is larger than that in Ge15. On the other hand, all the annealing films exhibit PD, and the degree of PD decreases from Ge5 to Ge25. In all cases, PD is reversible while PB is irreversible. The Ge/As ratio or the lone pair electrons in Se atoms that were suggested for PIEs in the chalcogenide films cannot account for the present results in the GeAsSe films. Nevertheless, Ge15 exhibits minimum PIEs during a continuous illumination process that could be the best option for waveguide fabrication.