Effect of Annealing Atmosphere on Structure and Properties in Chemically Deposited PbS Thin Films

Large area (13mm*13mm) PbS thin films with (200) preferred orientation were prepared by chemical deposition. The optical properties of PbS films with annealing treatment in various forming gases with different ratio of nitrogen-oxygen (100ml/min of N₂&O₂(3:1), 100ml/min of N₂&O₂(2:1), 100ml/min of N₂&O₂(1:1), 50ml/min of O₂) were deeply analyzed. X-ray diffraction (XRD), scanning electron microscope (SEM), high and low temperature test chamber and other test methods for photosensitivity were used to investigate the structure and photoelectric properties of PbS films. The results showed that with proper amount of oxidation (when nitrogen-oxygen ratio was 1:1), the impurity barrier tended to fully grow, impurity activation energy increased to 0.314eV, dark resistance reached up to 30.2MΩ, and the photoconductive sensitivity of PbS thin film under this process was about 4 times larger compared with air annealing. According to the analysis of XRD patterns and surface morphologies of films, it can be seen that nitrogen in this process was not only to prevent PbS thin films from excessive oxidation, but also inhibited the formation of surface defects and enhanced the stability of PbS device.