Molecular dynamics study of electronic temperature effects on the laser ablation of silicon

TL;DR

This study uses molecular dynamics simulations incorporating electronic temperature effects to better understand laser ablation of silicon, revealing significant differences in pressure and evaporation compared to traditional models.

Contribution

It introduces an interatomic potential dependent on electronic temperature for MD simulations, highlighting the impact of hot electrons on ablation dynamics.

Findings

Electronic temperature increases compressive pressure near the surface.

Enhanced evaporation of atomic clusters occurs with electronic temperature dependence.

Longer melt depth observed when electronic temperature effects are included.

Abstract

The molecular dynamics (MD) approach is an effective tool for investigating atomistic dynamical phenomena at the surface of materials under strong laser irradiation. Therefore, numerous laser ablation MD simulation studies have been conducted to date. However, in most MD studies, non-thermal and entropic effects via hot electrons on interatomic interactions that could cause significant differences in the simulation results are not considered. In this study, the MD simulation of the laser ablation of the Si surface was conducted using an interatomic potential whose parameters depended on the electronic temperature. Moreover, the results obtained with and without electronic temperature dependence were compared. The electronic temperature dependence resulted in an approximately four-times-greater compressive pressure near the surface, enhanced evaporation of atomic or smaller clusters, and slightly longer melt depth. Compared to the strong compressive pressure near the surface, the tensile pressure, which originated from the reflection of the compressive pressure wave at the surface, and ablation phenomena were less dependent on the electronic temperature.