CdZnTe thin films growth by RF sputtering for CdTe solar cells

Cadmium Zinc Telluride (CZT) films were deposited by co-sputtering of CdTe and ZnTe targets in an RF magnetron sputtering using various combinations of RF powers, and the effect of sputtering power on the properties of CZT films were studied using SEM, EDX, XRD, AFM and UV-VIS spectrophotometer. The SEM and AFM data shows that as the ratio of the CdTe: ZnTe RF power increases, so does the grains size and surface roughness of the samples. From the EDX results, it was found that the amount of Zn in the ternary reduces with the RF power ratio. The optical analyses of the films indicate that they have good absorption; with shallow absorption edge occurs in the range of 750-850 nm. The energy bandgap of the samples were found to vary between 2.04 eV-2.54 eV, which covers the range of most BSF materials used for CdTe solar cells. The study has thus shown the feasibility of using RF sputtering for the development of both absorber and BSF layer in one monolithic structure, for applications in CdTe thin film solar cells.