Study of non-reversible photostructural transformations in As₄₀S₆₀-xSex layers applied for fabrication of holographic protective elements

Abstract

Thin vacuum-evaporated layers of As₄₀S₆₀-xSex composition are investigated using Raman spectroscopy from the viewpoint of thermo- and photostructural transformations in them. These transformations are considered as changes in their network structure including three types of piramidal units AsS₃/₂, AsSe₃/₂ and AsS(Se)₃/₂ as well as As₄S(Se)₄ and S(Se)n fragments in its initial state. Annealing or light exposure result in polymerization of the molecular groups and the decreasing number of homopolar bonds, which is thermodynamically favorable. Characteristics of sensivity to photon and electron exposure were investigated. Diffraction efficiency perfomances of a microrelief fabricated using these layers are presented.