Effect of CdCl2 treatment on structural and electronic property of CdTe thin films deposited by magnetron sputtering

Abstract The structural and electrical properties of the magnetron sputtered CdTe thin films with subsequent CdCl 2 solution treatment have been studied with a major focus on the influence of CdCl 2 treatment to achieve high quality thin films. In this study, CdTe films with a thickness of 1.5 to 2 μm have been grown using the magnetron sputtering technique on top of glass substrate at an optimized substrate temperature of 250 °C. Aqueous CdCl 2 concentration varied from 0.3 mol to 1.2 mol with the annealing temperature from 360 °C to 450 °C. The surface roughness of the films increases with the increase of solution concentration, while it fluctuates with the increase of annealing temperature. The density of nucleation centers and the strain increases for the films treated at 360 °C with 0.3 M to1.2 M while the grain growth of the films reduces. However, these strains are released at higher annealing temperatures, resulting in reduced dislocation densities, structural defects as well as increased crystalline property and grain size. The carrier concentration increases with the increase of treated CdCl 2 concentration and subsequent annealing temperature. The highest carrier concentration of 1.05 × 10 14 /cm 3 was found for the CdTe thin films treated with 0.3 M CdCl 2 solution followed by an annealing treatment at 420 °C for 20 min.