Simulation of dynamics of phase transitions in CdTe by pulsed laser irradiation

Numerical simulation of melting and solidification processes induced in CdTe by nanosecond radiation of ruby laser (λ = 694 nm, τ = 20 and 80 ns) and KrF excimer laser (λ = 248 nm, τ = 20 ns) taking into account components diffusion in melt and their evaporation from the surface has been carried out. Cd atoms evaporation has shown to essentially affect the dynamics of phase transitions in the near-surface region. Thus, in the case of the influence of ruby laser irradiation intensive surface cooling results in the formation of nonmonotone temperature profile with maximum temperature in semiconductor volume at the distance of ∼20 nm from the surface. The melt formed under the surface extends both to the surface and to the semiconductor volume as well. As a result of cadmium telluride components evaporation and diffusion in the melt the near-surface region is enriched with tellurium. The obtained melting threshold value of irradiation energy density is in a reasonable agreement with experimental data.