ZnTe thin films grown by electrodeposition technique on FTO substrates

Abstract

[EN] Zinc telluride (ZnTe) thin films are prepared potentiostatically from an aqueous solution bath containing ZnCl2, TeCl4 and LiCl on Fluorine Tin Oxide coated glass substrate to investigate its suitability as a material for solar cell technology. The appropriate potential region where formation of stoichiometric ZnTe semiconductor occurs is found to be close to −0.85 V versus Ag/AgCl. X-ray diffraction results have indicated that all electrodeposited films have cubic structure. Quantitative analysis of energy dispersive X-ray analysis results has shown that the composition ratio (Zn:Te) of films is around (1:0.99). A direct energy gap of 2.19 eV is determined by NIR–Vis– UV spectroscopy. The effect of annealing on the crystallinity and optical properties has been reported. Impedance measurements have revealed that all grown films present a p-type electrical conductivity with acceptor density NA=2.16×1019 cm−3. Furthermore, the impedance results are adjusted to an equivalent circuit having two capacitors in series (Helmholtz, CH and space charge, CSC) and two resistances RCT and RSC, which are associated with charge transfer processes.