Photosensitivity of pulsed laser deposited Ge20As20Se60 and Ge10As30Se60 amorphous thin films

Amorphous Ge20As20Se60 and Ge10As30Se60 thin films are fabricated by pulsed laser deposition. Prepared films are characterized in terms of their morphology, chemical composition, and optical properties. Special attention is given to the photosensitivity of the layers, which was studied by spectroscopic ellipsometry with as-deposited, annealed and exposed films by three different laser sources (593, 635, and 660 nm). The results show better photostability for Ge20As20Se60 thin films, where photoinduced change of optical band gap was found to be equal or less than 0.04 eV and these layers present almost zero photorefraction.