SYNTHESIS AND CHARACTERIZATION OF Cd_1-xZn_xS:Cu CRYSTALS BY CO-PRECIPITATION METHOD

Copper doped Cd 1-x Zn x S compounds were prepared by controlled precipitation method with 0≤x≤1. The samples were characterized by X-ray, chemical analysis, optical absorption, and SEM studies. The X-ray studies have indicated that the compounds have polycrystalline nature with mixed Hexagonal and Cubic structure of CdS with x=0–0.6, the structure changed to a prominent cubic structure of ZnS with x>0.6. Optical studies have shown that the grain size increased with x varying from 0–0.2 and then it decreased. It was also observed that the optical energy gap decreased with x till x ⋍ 0.2, attained a minimum with x=0.2 and then it increased gradually. The values of E g obtained for CdS and ZnS were 2.21 eV and 2.53 eV. The chemical homogeneity of the samples was also observed from the EDAX and noted that the sulfur and copper contents remained almost the same, and the decrease in Cd and increase in Zn atoms occurred systematically. The results were explained on the basis of different phases formed and the role of copper impurity.