The charge states of the divacancies which were introduced by the 5MeV self-implantation of doped material were investigated by using positron annihilation methods. At low dopant concentrations, the results agreed with the predictions of Fermi statistics. An anomalous singly-negative divacancy charge state was detected in heavily B-doped material. This was attributed to the introduction of new levels in the band-gap; due to the capture of B by divacancies. This resulted in B-divacancy complexes. An analysis of the positron annihilation spectra suggested that the B did not reside on a nearest-neighbour site near to the divacancy. Isothermal annealing experiments yielded an activation energy of 0.9eV for the migration of this defect.

Charge States of Divacancies in Self-Implanted Doped Si. S.Szpala, P.J.Simpson: Journal of Applied Physics, 2001, 89[11], 5991-6