Study of Hydrogen Diffusion in Crystalline Silicon

Examination of the hydrogen diffusion process in single-crystal silicon has been carried out utilizing two pronged approaches: (1) a simplified one-dimensional diffusion model, and (2) numerical solution of the complete set of coupled diffusion equations. Incorporation of hydrogen -trapping kinetics has been employed through the investigation of hydrogen passivation of defects in silicon and the various states of hydrogen that exist in the perfect silicon lattice. This semi-quantitative analysis has proven successful in explaining a number of fundamental complexities concerning the observed diffusion behavior of hydrogen in crystalline silicon which were heretofore unclear. In addition, the numerical solution of the coupled diffusion equations incorporating trapping kinetics has allowed the duplication of existing experimental data in the form of hydrogen concentration versus depth profiles. The accuracy of these simulations lends strong support to the accepted view that the trapping of hydrogen has a profound influence on its diffusion behavior in silicon and serves to verify the validity of our trapping kinetics model for the migration of hydrogen within the silicon lattice. Consequently, we believe that this work represents a small, but firm, step toward a comprehensive understanding of the complex nature of the hydrogen diffusion process in crystalline silicon.