Characterization of the surfaces of CdTe(111) single crystals after laser processing

Autor: Gnatyuk, Dmytro V., Poperenko, Leonid V., Yurgelevych, Iryna V., Aoki, Toru
Zdroj: Proceedings of SPIE; September 2011, Vol. 8142 Issue: 1 p81421N-81421N-7, 732797p
Abstrakt: Optical properties and morphology of the opposite polar faces of CdTe(111) single crystals subjected to irradiation with nanosecond pulses of the second harmonic of a YAG:Nd laser in a wide range of energy densities have been studied by multiple-angle-of-incidence single-wavelength ellipsometry and atomic force microscopy. The ellipsometric data have been interpreted by the semi-infinite medium model and it is assumed that there are no films on the crystal surface. Also the one-layer model is applied and the crystal relief is considered as a top layer. The refraction n and absorption k indexes of the surface layer are calculated using the fundamental ellipsometric equation and method of thickness curves. Laser irradiation results in an increase in the refractive index of the CdTe surface layer due to laser-induced transformation of the surface structure and it is associated with enriching of the CdTe surface with tellurium. The surface morphology of the crystals is modified at higher laser pulse energy densities because of the beginning of melting of prominent irregularities and thin surface layer. The effects of irradiation with nanosecond laser pulses on the polar surfaces of CdTe(111) crystals are analyzed.
Databáze: Supplemental Index