Pulsed laser-induced phase transformations in CdTe single crystals

Kinetics of laser-induced phase transitions in CdTe has been studied by in situ (during laser processing) and ex situ (before and after laser irradiation) methods. The samples were irradiated in air by a ruby laser with pulse duration of 80 ns and energy density range from 0.02 to 0.5 J/cm2. Time-resolved reflectivity measurements were carried out at the wavelengths of λ1 = 1064 nm and λ2 = 532 nm. The time evolution of reflectivity for probing beams with photon energies below (λ1) and above (λ2) than the semiconductor energy gap was analyzed. The reflectivity value of CdTe at λ = 694 nm was measured versus irradiation energy density. The reflectivity was 0.28 at room temperature and 0.36 in the liquid phase. The changes in the surface morphology were studied by optical and atomic force microscopy for different energy densities of the laser irradiation.