ELECTROCHEMICAL DEPOSITION OF ZNFES THIN-FILM SEMICONDUCTORS ON TIN OXIDE SUBSTRATES

The electrodeposition of ZnFeS thin film semiconductors on tin oxide substrates in diethyleneglycol solution containing S-8, FeCl2 . 4H(2)O and ZnCl2 reagents was investigated. The potential region, where formation of the ZnFeS semiconductor occurs, was singled out between -0.6 and -1.0 V(SCE). Amorphous films were obtained after the deposition. Conversion from amorphous to a crystalline structure was achieved by annealing the semiconductors at 285 degrees C in Argon. Chemical and morphology characteristics were investigated by EDAX and SEM analyses. A direct relationship was observed between the Fe and Zn concentration in the electrodeposition bath and the Zn/Fe ratio in the deposits. Thin film XRD analysis showed the crystallographic structures of sphalerite and pyrrhotite. The optical properties of the thin film semiconductors changed as function of the Zn and Fe contents in the solution and in the films. The indirect energy gap transition varied from 0.37 to 3.1 eV, as the Zn/Fe ratio in the solution was increased. The suitable optical properties of the thin films and the low-cost preparation procedure appear as promising characteristics for the application of the ZnFeS system in solar energy conversion devices.