Activated transport in amorphous semiconductors. III. Bethe-lattice approach

Abstract

For pt.II see ibid., vol.18, p.3191 (1985). Using a Bethe-lattice approach the differential conductivity is calculated numerically on the basis of the tight-binding model of parts I and II of this series. Both hopping and tunnelling contributions to the transport are obtained within a small-polaron picture, treated to lowest order in the electron-phonon coupling. The results agree qualitatively and nearly quantitatively with the analytical theory of I, based on a mode-coupling approximation. In contrast to the latter no ad hoc assumption about the density of states has to be made, leading to a consistent phase diagram in the static limit.