Femtosecond ultrafast dynamics simulations of typical semiconductor materials under swift heavy ion irradiation

Abstract

Swift heavy ion (SHI) irradiation has long been used to evaluate the performance of radiation-hard semiconductor devices. However, the in-depth insight into its microscopic processes and damage evolution remains unclear. In this work, the ultrafast microscopic processes within femtosecond timescales under SHI irradiation of four typical semiconductor materials (Si, 4H-SiC, GaN, β-Ga2O3) are investigated by the coupling ab initio and two-temperature model (TTM) methods. The ab initio method is utilized to systematically calculate the temperature-dependent electronic thermodynamic parameters of four semiconductor materials and then incorporated into the TTM to reveal the significance of the intrinsic thermodynamic properties on thermal spike evolution under SHI irradiation. The results demonstrate that stronger electron–phonon coupling accelerates femtosecond thermal processes and promotes more efficient energy transfer from the electronic to lattice subsystems. Lower thermal conductivity suppresses energy diffusion within subsystems, leading to more pronounced energy spikes. These energy spikes induced by the SHI produce instantaneous molten zones where radius variations are correlated with the material melting threshold energy. Under 430 MeV Kr ion irradiation, instantaneous molten zones with radii of 4.64 and 5.70 nm are formed within femtoseconds in GaN and β-Ga2O3, respectively, while no melting occurs in Si or SiC. This work provides essential data for understanding the behavior and microscopic damage processes of semiconductor materials under extreme irradiation conditions.