Theory of hydrogen passivation of shallow-level dopants in crystalline silicon

The stable structures, vibrational modes, and passivation mechanisms of an interstitial hydrogen atom in boron- and phosphorus-doped crystalline silicon are determined by an ab initio pseudopotential method. Our calculated formation energies for passivated H-B and H-P complexes are 2.5 and 2.0 eV, respectively, as compared to a binding energy per H of 1.9 eV in an interstitial ${\mathrm{H}}_2$ molecule. The higher dissociation energy of H-B relative to H-P is consistent with recent experimental observations that show a more pronounced hydrogen passivation for shallow acceptors.