Hydrogen diffusion and passivation of shallow impurities in crystalline silicon

The role of hydrogen (H) in pure and doped silicon (Si) is elucidated by first-principles total-energy calculations for hydrogen in various charge states in pure Si and for hydrogen-boron complexes in Si. It is established that H acts as a donor in p-type material, confirming the passivation mechanism of shallow acceptors by H via compensation and complex formation. By exploring the entire energy surface for H in boron-doped Si, it is found that H can move on a spherical shell around B with an energy barrier of only 0.2 eV. The global energy minimum on the shell occurs for a position in the center of a Si-B bond. (author) 16 refs., 2 figs