Consideration of ac conductivity as evidence of localized tail states in amorphous chalcogenides

Abstract

Abstract The temperature dependence of the ac conductivity for As 2 Te 3 and TeAsSiGe films is given. Below 200°K, σ 1 ( ω ) ∞ T ; above 200°K, σ 1 ( ω ) rises more rapidly with T . Interpretation of σ 1 ( ω ) as due to hopping in localized states at the Fermi level and in tail states near mobility edges is discussed. An unsymmetrical density of states is discussed, and a high density of states at the Fermi level is considered to be consistent with optical absorption data.