Study Of Pure And SB-Doped CDSE_xTE_1-x Films Prepared By Vacuum Evaporation

Because the optical band gap can be adjusted continuously, CdSexTe1-x compound films can be prepared with a bandgap graded PV cell. Therefore CdSexTe1-x compound films has attracted many researchers in recent years. CdSexTe1-x films are popularly prepared by hot wall deposition technique. Pure CdSexTe1-x and Sb-doped CdSexTe1-x ternary thin films were prepared on glass substrates by vacuum evaporation in this paper. High purity CdTe, CdSe and Sb powder with different chemical composition ratio were used as a source material. Finally, these films were annealed with different temperatures in N2atmosphere for15minutes.The crystal structure, surface morphology, chemical composition, binding energy, optical and electrical properties of the films were examined using X-ray diffraction technique, Scanning electron microscopy, X-ray photoelectron spectroscopy, UV-visible spectrophotometer and Four probe resistivity measurement. The effects of composition (x), annealing, and Sb-doped on CdSexTe1-x thin films were analyzed.XRD results show that the films exhibit a cubic zinc blende structure with (111) preferred orientation. Linear variation of lattice constant with composition (x) is observed. Lattice constant decreases steadily with increasing x. Optical transmission spectrum shows that the absorption edges of CdSexTe1-x films are shifted to long wave with the increase of Se concentration passing through a maximum for x=0.75and then shifted to short wave. The minimum optical band gap is1.41eV for x=0.75. XPS results reveal that the main component of the films is the CdSexTe1-x compound. Characteristic peaks of Se, Te and Cd are all moved to the high energy side with the increase of x. The studies reveal that the crystallization, optical and electrical properties of the films can be improved by increasing heat treatment temperature and Sb-doped, but not change crystal structure. Sb-doped reduces its transmission ratio in the long wave region. The optical band gap and transmission ratio drops to minimum by doping2%Sb. Sb-doped reduces the resistance of CdSexTe1-x is much improved after doping Sb and drops to3.548×10-3Ω·cm by doping2%Sb.