Structural, optical and electrical properties of Cl-doped ternary CdZnS thin films towards optoelectronic applications

This paper reports the effect of chlorine doping on the structural, morphological, optical and electrical properties of spray deposited ternary CdZnS thin films. Cadmium chloride (CdCl2·2H2O), thiourea (SC(NH2)2) and ZnCl2·6H2O were used as precursors to prepare CdZnS thin films. Cl doping is achieved by adding NaCl with concentrations 0, 2, 4, 6 and 8 at.%. XRD analysis showed that the CdZnS and Cl-doped CdZnS films exhibit hexagonal crystal structure with a (0 0 2) preferential orientation. Film transparency increased with Cl doping and the band gap values exhibit a blue shift from 2.55 eV to 2.78 eV. Electrical studies showed that the CdZnS film resistivity decreased from 4.96 × 10−3 ohm-cm to 0.614 × 10−3 ohm-cm with Cl doping. The Raman studies confirmed the presence of defects in samples. Improved transparency, widened band gap and decreased resistivity values observed for the Cl-doped CdZnS films confirm that chlorine might be a suitable anionic dopant which can enhance the physical properties of CdZnS thin films.