Instability of nanocavities in amorphous silicon

Abstract
This letter demonstrates that, whereas nanocavities are quite stable in crystalline 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 implantation, followed by annealing at 850 °C. Amorphization of the c-Si surrounding the nanocavities led to their disappearance. Transmission electron microscopy, Rutherford backscattering, and channeling and time resolved (optical) reflectivity were used to provide details of the cavity instability process by studying the amorphous Si after implantation and subsequent crystallization. Two possible reasons are suggested for the instability of nanocavities in a-Si.