Dependence of the CdTe Melting Threshold on the Pulse Duration and Wavelength of Laser Radiation and the Parameters of Non-Equilibrium Charge Carriers

The dependences of the melting threshold of CdTe under the pulsed laser irradiation on the radiation wavelength л and the laser pulse duration тp are calculated with regard for the non-equilibrium character of charge carriers. Three components of the energy released at the thermalization of excited carriers under the nanosecond laser irradiation of CdTe in the fundamental absorption region are considered: the component that dominates immediately after the excitation, and the components released at the nonradiative bulk and nonradiative surface recombinations. Together, they determine the depth of heat penetration into the crystal and, therefore, its melting threshold. It is shown that the CdTe melting threshold grows from 2.6 to 4.75 MW/cm2, when л changes from 300 to 800 nm at тp = 20 ns. The changes in the non-equilibrium charge carrier parameters (the surface recombination rate, lifetime, and diffusion depth) are found to vary the CdTe melting threshold by at least 30%.