A mechanism for hole generation by octahedral B6 clusters in silicon.

The electronic structure and x-ray photoelectron spectra of silicon with octahedral B6 clusters are investigated using first-principles calculations. It is found that the B6 clusters act as double acceptors in silicon and that the simulated chemical shift of the B 1s orbital signals of the B6 clusters in x-ray photoelectron spectra coincides with the chemical shift of B 1s experimentally observed in as-implanted silicon at an extremely high dose of boron. These results reveal that the B6 clusters are the origin of hole carriers. We propose a mechanism of hole generation and a model of B6 cluster formation at implantation-induced divacancy sites. [ABSTRACT FROM AUTHOR]