Electrical and optical properties of amorphous semiconducting GeSe and GeSbSe films

Abstract

The electrical activation energy and optical band-gap of GeSe and GeSbSe thin films prepared by flash evaporation on to glass substrates have been determined. The conductivities of the films were found to be given by σ=C exp ( - E_a/KT), the activation energy E_a being 0.53 eV and 0.40 eV for GeSe and GeSbSe respectively. The optical absorption constant a near the absorption edge could be described by α ω = k ( ω - E₀)from which the optical band-gaps E₀ were found to be 1.01 eV for GeSe and 0.67 eV for GeSbSe at 300°K. At 110°K the corresponding values of E₀ were 1.07 eV and 0.735 eV respectively. The significance of these values is discussed in relation to those of other amorphous semiconductors.