Field effect on trigonal selenium crystals

Abstract

The field effect of trigonal selenium crystals is investigated as a function of temperature. The field mobility μF has the same temperature dependence as the conductivity and is of similar magnitude as the Hall mobility. This shows that surface states are of minor importance. At high values of the transverse voltage, the surface conductance exhibits a minimum which seems to indicate the formation of an inversion layer. The results are discussed in terms of a barrier model. It is shown that the minimum of conductance can be explained by a reduction of potential barriers at the surface in high electric fields.