Stationary Field Inhomogeneities in Homogeneous Semiconductors Due to Negative Differential Conductivity

摘要

Layer-like field inhomogeneities in homogeneous semiconductors, which have been shown to occur whenever the conductivity decreases faster than linearly with increasing field, are discussed using a reaction-kinetic model including the Poisson and transport equations. Stationary solutions when the negative differential conductivity is either due to field-dependent carrier concentration or to field-dependent mobility are obtained in the approximation that the diffusion term is negligible compared to the drift term in the transport equation. When diffusion is included, an analysis by the method of characteristics, previously applied to the case of field-dependent carrier concentration, is extended to the case of field-dependent mobility. In the appendices the results of this discussion are compared with those of discussions by Ridley and by Bonch-Bruevich and Kalashnikov. (Author)