Photo-induced optical effects in obliquely deposited amorphous Se-Ge films

The photo-induced shift in the optical transmission edge has been studied in obliquely deposited amorphous Se75Ge25 films. The effect of preannealing, exposure, postannealing, and film thickness on the photo-induced optical changes have been investigated. Our studies reveal that the photoeffects consist of two distinct contributions: photothermal and photo-optical. Whereas the photothermal effect decreases with angle of deposition as well as annealing, the optical effect increases rapidly with obliqueness. The nature and the respective contributions of these two processes have been established