A model of conduction in polycrystalline silicon films

Abstract

Conductivity and Hall measurements have been performed on n-type and p-type polycrystalline silicon films over a wide range of temperatures (30–400 K). We present an interpretation of the electrical behavior of polycrystalline semiconductors which for the first time takes into account intergranular fluctuations in potential. In this model, random distribution of potential among grains and fluctuations in barrier heights at grain boundaries (GB) result from nonuniformities in the grain size, impurity concentrations, and GB state densities. We separate the carriers into localized carriers and free carriers. This model explains both the high and low temperature conduction regimes. We estimate the intergranular disorder parameter and the threshold energy for several phosphorus or boron-doped silicon samples.