Cavities in monocrystalline specimens were shown to act as gettering centres for the vacancies which were produced during ion implantation. The effect of gettering was seen as an increase in their total volume. The implantation of 20keV He to a dose of 2 x 1016/cm2, and heat treatment (850C, 4h), produced cavities. Vacancies were supplied by the subsequent implantation of 8 x 1015/cm2 of He. In this case, the vacancy-gettering efficiency was found to be equal to 0.53 vacancies/ion. This was about 4 times higher when compared with the case where the same implantation was performed on a virgin crystal. It was noted that He acted as a stabilizer of the vacancies which were produced during implantation. The differential vacancy-gettering efficiency was found to increase with the He dose. That is, it amounted to about 0.13 vacancies/ion at 8 x 1015/cm2, 0.4 vacancies/ion at 2 x 1016/cm2, and 3.8 vacancies/ion at 2.8 x 1016/cm2.

Vacancy-Gettering in Silicon - Cavities and Helium-Implantation F.Corni, R.Tonini, S.Frabboni, C.Nobili, G.Calzolari, S.Masetti, P.Tamarozzi, G.Pavia, G.F.Cerofolini: Solid State Phenomena, 1999, 69-70, 229-34