Plume analysis during pulsed laser ablation of silicon in hydrogen gas

Abstract

Recently, surface passivated Si nanocrystallites are prepared by pulsed laser ablation (PLA) of Si target in hydrogen gas. Plume analysis during PLA is one of the available methods to clarify a mechanism of surface hydrogenation. We observed plume emission by time- and space-resolved spectroscopy. The dominant species were exited neutral Si atoms and SiH species when the delay time is longer than 100 ns. The Si atoms and SiH species existed throughout the plume. This indicates that nanocrystallites grow in the mixture of Si and SiH vapor. The surfaces of Si nanocrystallites are considered to be hydrogenated by SiH species during the growth. It seems that surface hydrogenation is not due to the spatial separation of Si and H species but due to surface reaction with SiH and/or Si species.