Disorder-induced carrier localization in silicon surface inversion layers

Abstract

Potential fluctuations in silicon surface inversion layers give rise to carrier localization in this quasi‐two‐dimensional system. A semiclassical model is used to evaluate the density of states in the tails below the bands of extended states. To investigate the carrier transport in the tails, we have measured the Hall mobility at lower temperatures and carrier concentrations than has previously been reported. The observed results cannot be accounted for by thermal excitation to extended states above a mobility gap or by thermally activated hopping in localized states. An explanation based on percolation theory is suggested.