Millisecond kinetics of photo-darkening/bleaching in xGe45Se55-(1−x)As45Se55 chalcogenide amorphous films

Photosensitivity of thermally evaporated chalcogenide amorphous films of xGe45Se55-(1−x)As45Se55 (x = 0, 0.25, 0.5, 0.75, 1) composition is investigated when exposed to the laser light of 660 nm wavelength. The photo-induced effects transition from photodarkening (PD) to photobleaching (PB) as Ge45Se55 x increases from 0 to 1. The degree of PB correlates with the concentration of Ge–Ge homopolar bonds. The kinetics of PD and PB can be well described by a stretched exponential function. The dynamic response of PB is much faster than that of PD films in the present glass system.