Effects of CdCl ₂ thermal annealing on CdZnTe thin films deposited by close-spaced sublimation

The CdZnTe polycrystalline thin films were deposited by close-spaced sublimation (CSS) and then annealed with CdCl ₂ coating. The influences of the CdCl ₂ annealing on the morphology, composition, structure and optical properties of the films were studied by SEM, EDS, XRD, UV spectrophotometer, and I-V measurements. The SEM results show that after annealing the grains are more uniform, and the grain sizes are increased significantly. The XRD results show that the FWHM of the (111) peak, which is the strongest diffraction of the CdZnTe films, reduced and the (111) texture is enhanced after annealing. The optical transmittance decreases and the forbidden edge shifts toward longer wavelengthwith, indicating the decrease of the optical band gap. The resistivity of the film decreases by two orders of magnitude after annealing.