Hydrogen passivation of grain boundaries in polysilicon. Computer simulation

Problem of a hydrogen diffusion along a grain boundary during the process of hydrogen passivation of grain boundary traps and degradation of passivated polysilicon was considered. Possible mechanisms of hydrogen interaction with grain boundary were discussed. It was shown that grain boundary diffusivity for low angle and near-special boundaries is equal to that for grain. The dependence of grain boundary diffusion on both concentration of the grain boundary centers of a hydrogen capture and hydrogen-trap bond energy was analyzed. It was found that the depth of passivation h approximately tⁿ, n > 1/2 . The n value depends on N^T and the bond energy E. When N^T → ∞ and E → ∞, n → 1. Parameters of grain boundary diffusion were outlined to depend on boundary structure. EBIC measurements have shown that both passivation of grain boundaries and their degradation are different for different boundaries.