Self-assembled growth and optical emission of silver-capped silicon nanowires

摘要

Structured silver-capped silicon nanowires were fabricated via electroless metal deposition on a silicon wafer in an ionic silver HF solution through selective chemical etching. Their formation mechanism was explained on the basis of self-assembled localized microscopic electrochemical cell model. The metal-semiconductor composite nanostructure was found to have a strong ultraviolet-emitting property with an emission peak position at 330 nm. The intensity of the peak nonmonotonously varies with annealing temperature and time, but its position remains unchanged. Emission and excitation spectral analyses suggest that the ultraviolet emission is closely related to the existence of silver vacancy defects in silver nanocaps formed during sample fabrication. A specific vacancy density is required to produce the strong ultraviolet emission.