Wavelength dependence of laser-induced excitation dynamics in silicon

TL;DR

This study numerically investigates how laser wavelength influences excitation dynamics, damage threshold, and carrier-phonon interactions in silicon, considering band-gap effects and using a combined 3TM and FDTD approach.

Contribution

It introduces a comprehensive numerical model combining Three-Temperature Model and FDTD to analyze wavelength-dependent excitation and damage in silicon, including band-gap renormalization effects.

Findings

Damage threshold varies with wavelength and pulse duration.

Inter-band excitation, plasma heating, and electron-phonon relaxation compete to determine damage.

Model results align reasonably with experimental data.

Abstract

Effect of laser wavelength on the carrier-phonon dynamics and damage threshold of silicon is studied numerically. Laser excitation dynamics in silicon is studied using Three-Temperature Model (3TM). We consider the evolution of electron, hole, and lattice temperatures separately and including band-gap re-normalization effect on optical properties of silicon. Finite Difference Time Domain method is used to model the laser field. Damage threshold calculated using the 3TM is in reasonable agreement with the experiments. Our results indicate that the competition of inter-band excitation, plasma heating, and electron-phonon relaxation process defines the damage threshold for various wavelengths and pulse durations.