Modeling ultrafast out-of-equilibrium carrier dynamics and relaxation processes upon irradiation of hexagonal silicon carbide with femtosecond laser pulses

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 behavior of laser-induced out-of-equilibrium carriers, a real-time simulation based on density-functional theory 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 (i.e., thermal equilibration between carrier and lattice through carrier-phonon coupling) 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 ~1.88Jcm-2. This approach of linking real-time calculations, transient optical properties, and TTM modeling, has strong implications for understanding both the ultrafast dynamics and processes of energy relaxation between carrier and phonon subsystems and providing a precise investigation of the impact of hot-carrier population in surface damage mechanisms in solids.