The dependence of Zn content on thermal treatments for Cd1−xZnxTe thin films deposited by close-spaced sublimation

CdZnTe thin films were deposited on FTO (SnO2: F)-coated glass substrates by close-spaced sublimation method and then annealed under different conditions. The influences of the three thermal treatments on the structure, morphology, composition and optical properties of the CdZnTe thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL) and Raman spectroscopy. The better crystalline quality can be obtained after any of three thermal treatments as evidenced by XRD, SEM, PL and Raman spectroscopy. The composition is homogeneous in depth for the as-deposited films and those upon annealing after CdCl2, while for films upon annealing both directly in vacuum and with ZnCl2 treatment, the inhomogeneity of Zn composition in depth, due to the loss of Cd atom at surface, can be evidenced by XRD, EDS and PL results. After annealing with ZnCl2 treatment, the Zn composition can be increased most notably by 1.5-2 times to around 7-10%.