Nanocavities in Si substrates, formed by conventional H implantation and thermal annealing, were shown to evolve in size during subsequent Si irradiation. Both ex situ and in situ analytical techniques were used to demonstrate that the mean nanocavity diameter decreases as a function of Si irradiation dose in both the crystalline and amorphous phases. Potential mechanisms for this irradiation-induced nanocavity evolution were considered. In the crystalline phase, the observed decrease in diameter was attributed to the gettering of interstitials. When the matrix surrounding the cavities was amorphized, cavity shrinkage may be mediated by one of two processes: nanocavities could supply vacancies into the amorphous phase and/or the amorphous phase may flow plastically into the nanocavities. Both processes yield the necessary decrease in density of the amorphous phase relative to crystalline material.

Direct Observation of Irradiation-Induced Nanocavity Shrinkage in Si. X.F.Zhu, J.S.Williams, M.J.Conway, M.C.Ridgway, F.Fortuna, M.O.Ruault, H.Bernas: Applied Physics Letters, 2001, 79[21], 3416-8