Instability of nanocavities in amorphous silicon

This letter demonstrates that, whereas nanocavities are quite stable in cry stalline Si (c-Si), they are unstable in amorphous Si (a-Si). This behavior is illustrated by introducing a band of nanocavities into c-Si by H implan tation, followed by annealing at 850 degrees C. Amorphization of the c-Si s urrounding the nanocavities led to their disappearance. Transmission electr on microscopy, Rutherford backscattering, and channeling and time resolved (optical) reflectivity were used to provide details of the cavity instabili ty process by studying the amorphous Si after implantation and subsequent c rystallization. Two possible reasons are suggested for the instability of n anocavities in a-Si. (C) 1999 American Institute of Physics. [S0003-6951(99 )01916-6].