Field-dependent carrier transport in non-crystalline semiconductors

Abstract

An electric field dependence of the d.c. conductivity and of the trap-limited carrier drift mobility is shown to occur in a range of non-crystalline semiconductors. Furthermore, the functional form of the dependence is found to be closely similar in each case. This behaviour is examined in terms of the models commonly proposed to explain field-dependent transport, but the data do not appear to be consistent with such models. It is suggested that the dependence may be due to a field modification of parameters controlling carrier motion in the region of the ‘mobility edge', but a quantitative analysis in such terms does not appear possible at present.