The Anderson transition in silicon inversion layers: the origin of the random field and the effect of substrate bias

Abstract
The purpose of this paper is to present results on and discuss the origin of Anderson localization in the inversion layer. Evidence is given for the existence of both negative and positive charges at the Si/SiO$_{2}$ interface. The negative charges contribute at least in part to the slow states at the Si/SiO$_{2}$ interface. The origin of these charges is discussed and a model proposed which provides an explanation of the conflicting reports on the value of minimum metallic conductivity, and the change in the extent of the localization as the distance between the carriers and the Si/SiO$_{2}$ interface is changed. It is suggested that in a two dimensional system long range potential fluctuations increase the minimum metallic conductivity above the value predicted, and found experimentally, for (the Anderson model with) short range potential fluctuations.