Electroabsorption in disordered solids: selenium

Electroabsorption data are presented for a number of amorphous chalcogenide semiconductors. Particular emphasis is placed on those obtained for amorphous selenium for which evidence is presented which suggests that the electroabsorption is associated with a quadratic Stark effect of localized excitations in the Se 8 rings. For this element the electroabsorption curves reveal subtle differences in the properties of evaporated films prepared under different conditions. The possible application of the electroabsorption technique to determine whether or not the boundary between extended and localized states in amorphous materials is sharply defined, is also discussed.