Surface state of CdTe crystals irradiated by KrF excimer laser pulses near the melting threshold

Abstract

We have studied pulsed-laser-induced melting and following crystallization of the surface of CdTe crystals subjected to irradiation with nanosecond KrF ( λ=248 nm) excimer laser pulses. The surface state, morphology and reconstruction of the surface layer of (1 1 1) B oriented CdTe wafers were investigated by measurements of time-resolved optical reflectivity, atomic force microscopy and reflection of high-energy electron diffraction. It was established that a jump in the reflection coefficient of a probe He–Ne beam, increase in the surface smoothness and change in the crystallinity of the surface layer occurred at the certain threshold value of laser pulse energy density W m≈50 mJ/cm 2. The peculiarities of the laser-induced melting and transformation of the structure of CdTe surface as dependence of KrF excimer laser energy density were discussed.