Characterization of functional layers of CdTe crystals subjected different surface processing

The surface functional layers of commercial detector-grade CdTe crystals after commonly used surface treatments as polishing chemical etching in bromine-containing solutions and laser annealing with nanosecond pulses of the second harmonic of YAG:Nd laser are characterized. Effects of etching and irradiation with energy density near the melting threshold on the CdTe surface properties are studied using ellipsometry and photoluminescence and also crystals after storage in air were used. The intrinsic emission band at 1.56 eV and broad defect band peaked at 1.45 eV are found in the PL spectra, excited by a semiconductor laser with wavelength of 405 nm at 80 K. The emission in 1.45 eV was associated with carrier recombination at the defects in the surface region, so called the surface state band.