Effect of selenization temperature on the formation of CZTSe absorber layer

Cu${}_2$ZnSnSe${}_4$ (CZTSe) thin-films were deposited on soda-lime glass (SLG) and Mo/SLG substrate by the thermal evaporation method. The deposition was followed by two-step annealing in Se atmosphere. It was found that the selenization temperature significantly affects the phase, surface morphology, optical properties and electrical properties of the films. The crystallinity of the films has been improved with a variation of annealing temperature from 400 °C to 500 °C. With an increase in annealing temperature binary phase of the film also disappeared. The optical band gap of the CZTSe film has varied from 1.33 eV to 1.12 eV with the variation of selenization temperature. The impurity present in the film also reduced with the increase in selenization temperature. This work gives the idea of the effect of selenization temperature on structural, optical and electrical properties of CZTSe film deposited using thermal evaporation technique. The good-quality film obtained can be further processed for device application.