Influence of grain boundary recombination velocity and grain size on the minority carrier lifetime in polycrystalline semiconductors

The effective minority carrier lifetime in polycrystalline semiconductors is determined in terms of the grain size and the recombination velocity at the grain boundaries. The effect of the grain boundaries is to reduce the effective lifetime when the grain size is smaller than few diffusion lengths. By comparison of the experimental with the theoretical results it is possible to determine the grain boundary recombination velocity. Excellent agreement is observed between theory and experiment in polysilicon.