Kinetic modeling for hydrogen passivation of polycrystalline silicon

The introduction of monatomic hydrogen into polysilicon grain boundaries has great potential for improving photovoltaic device efficiencies for thin-film and ribbon material. To optimize this process a more complete understanding of the relevant chemistry and kinetics is required. We discuss here two kinetic models of the passivation process: a one-dimensional Fickian model which is computationally easy and produces diffusion coefficients in good agreement with those in the literature and a two-dimensional model which though computationally complex provides a more accurate physical representation of the passivation process and more realistic grain-boundary diffusion coefficients for monatomic hydrogen. Both models appear to have practical utility for optimizing and understanding the passivation process. The nature of the site filling reaction is also discussed.