Layer-Like Field Inhomogeneities in Homogeneous Semiconductors in the Range of "N-Shaped Negative Differential Conductivity"

Abstract

Characteristic layer-like field inhomogeneities are shown to occur in homogeneous semiconductors if the decrease in conductivity is stronger than linear with increasing field. These inhomogeneities are discussed generally in a model using Poisson and transport equations, and the fact that the neutral density of electrons and/or the mobility decreases with increasing field strength. The method of characteristics is used for discussion in order to facilitate analysis of the experimental observations. Further experimental results about layer-like field inhomogeneities in CdS concerning domain width and field strengths, influence of optical excitation and quenching, and net charging of CdS crystals are given and show good agreement with the proposed theory.