Dependence of optical absorption of amorphous InSe films on temperature of heat treatment

Amorphous In _XSe _{1- X} thin films of thickness ⋍2700 Å are prepared by vacuum evaporation. The optical gaps E^opt_g are determined from the absorption spectrum of the InSe films heat treated at different temperatures and for different periods of time. The increase in the values of E^opt_g of a-InSe films with heat treatment is interpreted in terms of density of states model of Mott and Davis and explained as due to the saturation of bonds in the amorphous solid.