Structure, optical properties and their photo-induced changes in AsxSe100 − x (x = 50, 57.1, 60) amorphous thin films prepared by pulsed laser deposition

Thin amorphous AsxSe100 − x (x = 50, 57.1, 60) films were prepared using pulsed laser deposition technique (PLD). Raman scattering spectra and some optical properties (optical gap, index of refraction) of as-deposited films as well as light-induced changes of their structure and properties were studied. The structure of PLD films with higher As-overstoichiometry (As57.1Se42.9, As60Se40) is different from the structure of corresponding bulk glasses (keeping the chemical composition constant) and is formed mainly by As-based pyramids [As(Se,As)3/2], or As4Se4, As4Se3 molecules, and possibly As4 clusters. Light-induced changes of the structure of As-Se PLD thin films, giant changes of the index of refraction values and also significant photo-induced bleaching of the films after the exposure of as-deposited films were observed and discussed.