Interaction of UV photons with solid and nanocrystalline silicon

TL;DR

This paper investigates how UV photons interact with bulk and nanocrystalline silicon, revealing two distinct ion populations and highlighting a significant non-thermal ion component in laser-induced plumes.

Contribution

It uncovers the existence of a non-thermal ion population in silicon during UV laser irradiation, a novel observation in the field.

Findings

Two ion populations identified: rapid and slow.

Surface charge repulsion causes the rapid ion ejection.

Non-thermal ion population constitutes a significant part of the plume.

Abstract

The studies of interaction of the UV photons with bulk and nanocristalline silicon by time-of-flight (TOF) mass-spectrometry allowed to reveal two populations of Si ion monomers. The first rapid population ejected even at low laser fluences is attributed to Colombian repulsion between the surface charges which are induced by emission of the photoelectrons. When the laser fluence increases, the second slow ion population appears. This population originates from the thermal processes in the irradiated material. The original result of this work is the observation of the non-thermal ion population which represents a considerable part of the laser-induced plume.