Conductivity in polycrystalline silicon—physics and rigorous numerical treatment

A new model for electrical conductivity in polycrystalline silicon is presented. Current transport across the grain boundaries is considered to be controlled by diffusion and drift mechanisms with the boundaries being modeled as monocrystalline layers of heavy concentrations of traps and scattering centers. For the first time a complete numerical solution of Poisson´s and continuity equations has been computed for grains and grain boundaries not relying upon fitting factors. The input data needed are grain size, grain boundary width, density, and energetic distribution of traps and mobility values at the boundaries. Comparisons with various measurements of the resistivity and the effective mobility of polysilicon show good agreement with this model.