Modelling ultrafast non-equilibrium carrier dynamics and relaxation processes upon irradiation of hexagonal Silicon-Carbide with femtosecond laser pulses

TL;DR

This paper combines real-time DFT simulations with a Two-Temperature model to investigate ultrafast non-equilibrium carrier dynamics and surface damage in hexagonal Silicon Carbide caused by femtosecond laser pulses.

Contribution

It introduces a novel integrated approach linking real-time DFT, transient optical properties, and TTM to study ultrafast carrier dynamics and surface damage mechanisms.

Findings

Surface damage occurs at fluence ~1.88 J/cm².

Hot carrier dynamics significantly influence surface damage.

First-time linkage of real-time calculations with TTM for SiC.

Abstract

We present a theoretical investigation of the yet unexplored dynamics of the produced excited carriers upon irradiation of hexagonal Silicon Carbide (6H-SiC) with femtosecond laser pulses. To describe the ultrafast behaviour of laser induced out-of-equilibrium carriers, a real time simulation based on Density Functional Theory (DFT) methodology is used to compute both the hot carrier dynamics and transient change of the optical properties. A Two-Temperature model (TTM) is also employed to derive the relaxation processes for laser pulses of wavelength 401 nm, duration 50 fs at normal incidence irradiation which indicate that surface damage on the material occurs for fluence ~1.88 Jcm-2. This approach of linking, for the first time, real time calculations, transient optical properties and TTM modelling, has strong implications for understanding both the ultrafast dynamics and relaxation processes and providing a precise investigation of the impact of hot carrier population in surface damage mechanisms in solids.