Theory of conduction in polysilicon: Drift-diffusion approach in crystalline-amorphous-crystalline semiconductor system—Part I: Small signal theory

A theory of conduction in polycrystalline silicon is presented. The present approach fundamentally differs from previous theories in its treatment of the grain boundary. This theory regards the grain boundary as amorphous semiconductor in equilibrium contact with crystalline grain. The model explains the electrical properties of polysilicon in terms of the electronic and structural parameters of the material and is in excellent agreement with the experimental data. The formulation is applicable for arbitrary grain size, temperature, doping concentration, and applied voltage. Specifically, the temperature dependence of resistivity is explained in terms of conduction channels inherent in the amorphous grain boundary. Also, this paper explicitly compares the previous emission theories with the present model in terms of voltage partition scheme and I - V predictions.