Cd1−xZnxTe thin films formed by non-aqueous electrochemical route

Polycrystalline thin films of graded band gap ternary cadmium zinc telluride (Cd_1−xZn_xTe) have been electrodeposited in a non-aqueous bath onto an indium tin oxide (ITO) coated glass cathode. Ethylene glycol was used as the non-aqueous medium. The cathodic electrodeposition of the ternary semiconductor Cd_1−xZn_xTe was studied using cyclic voltammetry in conjunction with photovoltammetry, optical, compositional, structural measurements and surface morphology. It is shown that the band gap of this alloy can be tuned from 1.42 to 2.21 eV by controlling the Cd:Zn mole fractions. X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX) measurements showed formation of Cd_1−xZn_xTe, where x varied between 0 and 1. It was found that the observed XRD reflections of all the samples index to the cubic phase of the Cd_1−xZn_xTe. The direction of the thermoemf developed in Cd_1−xZn_xTe films has also been shown to be opposite to the thermoemf for binary CdTe films. The resistivity rises with increase in the band gap indicating formation of a continuous solid solution of CdTe and ZnTe in the ternary phase Cd_1−xZn_xTe. The electrodeposited films have also been shown to possess polycrystalline pyramidal grains with compact and void free morphology.