EFFECTS OF DOPANT'S PROFILE ON PHYSICAL PROPERTIES OF ZnTe THIN FILMS

ZnTe thin films of 300nm thickness were prepared on glass substrates by thermal evaporation. These thin films were annealed in vacuum at 400 degrees C for an hour, thereafter these films were immersed in Cu(NO3)(2 center dot)H2O solution (1g/1000ml) for 20 minutes for Cu doping. Furthermore these doped samples were annealed in vacuum for diffusion of Cu in thin films for different annealing temperatures (one sample as doped, samples annealed after doping at 100 degrees C-400 degrees C) for one hour with interval of 100 degrees C. The crystalline nature and other structural parameters like lattice parameter, dislocation density and microstrain were analyzed by X-ray diffraction (XRD). The optical properties, such as transmission spectra, absorption coefficient, band gap and optical density were investigated with a UV-VIS-NIR spectrophotometer. The determined band gap was shifted from 2.22eV to 2.19eV with annealing. The resistivity of as doped sample was 148 Omega-cm and after annealing at 400 degrees C it was reduced to 30 Omega-cm. The conductivity type was investigated by hot probe method and was found p-type.