Photostructural transformations in amorphous Ge-S thin films: a light-scattering study

Reversible changes of the Raman spectra by the cycle of band-gap laser irradiation and annealing (storing in the dark) has been observed for amorphous Ge20S80 thin films for the first time. The observed changes in the region of stretch vibrations of the chalcogenide atoms is direct evidence for the occurrence of gross structural changes in local bonding configuration cased by optical irradiation. It has been shown that under the laser irradiation the bonding tendency of the chalcogenide atoms is to form rings rather than chains, i.e. the cis-conformation is preferred over trans-conformation.