Investigation On The Properties Of Re-Doped CdTe Thin Film Prepared By Vacuum Evaporation

Nd-doped and Dy-doped CdTe thin films were prepared by vacuum evaporation on glass substrates, and were annealed at 300℃,400℃,500℃in nitrogen. The characteristics of the samples were tested by X-ray diffraction instrument,X-ray photoelectron Spectrograph and ultraviolet-visible spectrophotometer. According to the result of the test, we analysed and optimized the preparation process of the CdTe thin film. At the same time, the influences of the Nd-doping and Dy-doping on the CdTe thin film was studied.The experimental results showed that the better CdTe thin films were prepared when the mixture ratio of high pure Cd and Te was Cd:Te=1:0.6. When the samples were annealed at T=500℃and t=10min, we can obtain pure polycrystalline CdTe thin films. When the annealing temperature was lower, there was Te phase in the CdTe thin films. Along with the rise of the annealing temperature, the Te phase content in the films was reduced, and the crystal structure of the samples was turned into pure CdTe phase gradually.The influence of rare-earth doping on the crystallography and optical characteristics of the CdTe thin films was evident. The combination of CdTe was restrained by rare-earth doping, and preferred orientation of crystal plane (111) was observed. With rare-earth doping , the content of Te phase was increased in the CdTe thin films at lower annealing temperature. Nd-doping led to the lattice constant and the crystal cell volume increased, optical transmission increased, and the optical band gap decreased slightly. Dy-doping led to the grain size increased and the optical band gap decreased evidently.