Screening effect of binding of P-Si-H complex in silicon

We have investigated hydrogen passivation of phosphorus(P) donors in heavily doped n-type silicon and reactivation of P donors due to dissociation of the formed P-Si-H complex as a function of the donor concentration. We used a remote-treatment method of atomic hydrogen for introduction of H atoms and electron spin resonance(ESR) for directly detecting P donors. We find from these experiments that the passivation fraction strongly depends on the donor concentration and that the recovery stage of P donors moves to higher temperatures in isochronal annealing with decreasing the donor concentration. The most effective substrate temperatures for hydrogen passivation are also found to range between 100 and 120 degrees C. These results suggest that the binding of the P-Si-H complex partially due to the Coulomb interaction decreases with increasing the P concentration. This is probably caused by screening effect of conduction electrons to Coulombic attraction between Si-+delta ind H--delta.