Electrical Properties of Silicon Films on Sapphire Using the MOS Hall Technique

Abstract

An experimental technique is described for determining the electrical properties of thin semiconducting films as a function of distance from the surface. The method is applied to silicon on sapphire films nominally 1 μ thick and doped n and p type on the order of (2–6)×10¹⁶/cm³, and the variation in average mobility and carrier concentration with depth into the layer is determined. A physical model for the variation of these parameters in the films is proposed which fits the experimental data and it consists of linearly decreasing mobility and constant impurity profile. The existance of a significantly wide nonconducting sublayer within the film is also suggested. It is found that the postulated model is successful in accurately predicting the actual surface concentration.