Novel non-thermal Ablation Mechanics in the Laser Ablation of Silicon

TL;DR

This paper explores unique non-thermal ablation mechanisms in silicon during ultra-fast laser ablation, revealing excitation-dependent dynamics like melting and Coulomb explosions through large-scale atomistic simulations.

Contribution

It introduces a novel simulation approach combining thermal-spike models with modified interatomic potentials to study non-thermal ablation in silicon.

Findings

Identification of excitation-dependent phase diagram of silicon

Observation of non-thermal melting and Coulomb explosions

Development of atomistic simulation framework for ultra-fast laser ablation

Abstract

We investigate the non-thermal material dynamics of strongly excited silicon during ultra-fast laser ablation. In contrast to metals, silicon shows strongly excitation-dependent interatomic bonding strengths, which gives rise to a number of unique material dynamics like non-thermal melting, Coulomb explosions and altered carrier heat conduction due to charge carrier confinement. In this study, we report novel non-thermal ablation mechanisms in the ultra-fast single shot laser ablation of silicon and perform large scale massive multi-parallel simulations on experimentally achievable length scales with atomistic resolution. For this, we model the ultra-fast carrier dynamics utilizing the Thermal-Spike-Model coupled to Molecular Dynamics simulations and include the accompanied excitation-dependent nonthermal bonding strength manipulation by application of the excitation-dependent modified Tersoff Potential. Further, we present first results on the systematic construction of the excitation-dependent phase diagram of silicon by thermodynamic integration.