Photoluminescence of CdZnTe thick films obtained by close-spaced vacuum sublimation

Polycrystalline Cd1−xZnxTe thick films with thicknesses of about 30 μm have been deposited on a Mo coated glass substrate by means of close-spaced vacuum sublimation technique. X-ray diffraction measurements have shown that the films obtained have only cubic zinc blende phase. The influence of Zn concentration on the photoluminescence (PL) spectra of Cd1−xZnxTe films was investigated. This let us determine the nature and energy structure of the intrinsic defects and residual impurities in the films. The presence of the most intense acceptor bound exciton A°X-line for x=0.10 and the lines of localized excitons (x=0.32−0.44) in PL spectra of Cd1−xZnxTe films indicates their fairly good optical quality as well as the p-type conductivity. There were also other intensive broad PL bands, caused by the recombination of donor-acceptor pairs involving complex acceptor centers, extended defects of dislocation type, and microstress in the films. It was also established a correlation between the broadening of exciton lines and the values of microstress in Cd1−xZnxTe thick films. Taking into account the energy position of exciton lines, the concentration dependence of the band gap for the Cd1−xZnxTe thick films is presented.