A.C. Conduction in Amorphous Semiconductors

Abstract

The recent developments in the theoretical and experimental study of frequency-dependent conductivity in amorphous semiconductors are reviewed, emphasising particularly on chalcogenide glasses. The striking similarity of a.c. conduction in quite different disordered solids is compared and discussed in terms of experimental results, modelling, and computer simulations. After giving an overview of experimental results, an existing macroscopic and a microscopic model are reviewed. More specifically, the factors such as random and non-random spatial distributions of electrically active centres responsible for the a.c. conductivity have been highlighted. Additionally, we have briefly discussed various aspects of a.c. loss behaviour on chalcogenide glasses such as effect of temperature, composition, doping, and other material properties. It is concluded that the a.c. conduction at intermediate to high temperatures is accounted for by the correlated barrier model, whereas at sufficiently low temperatures the behaviour is  related to the atomic tunnelling.