Preferential amorphization and defect annihilation at nanocavities in silicon during ion irradiation

Si containing a band of nanocavities has been irradiated with Si+ ions at e levated temperatures to study interactions of irradiation-induced defects w ith open volume defects. For irradiation at 100 degreesC, nanocavities are shown to be preferential nucleation sites for amorphization. It is proposed that this behavior occurs to minimize the local free energy, whereby less dense amorphous Si is free to expand into the cavity open volume. Furthermo re, for irradiation at 300 degreesC, cavities are very efficient sinks for Si interstitials during irradiation, leaving a region denuded of interstiti al-based clusters surrounding each nanocavity. (C) 2000 American Institute of Physics. [S0003-6951(00)01552-7].