The study of lead sulfide films The behaviour at low-temperature thermal treatment

The influence of annealing temperature on the sheet electrical resistance in the dark ( R□d) and the photosensitivity ( S) of the chemically deposited PbS thin films (thickness, 0.12–0.20 μm) was studied. By thermal treatment in air at 75–150°C, the parameters were increased, but after keeping the samples on anhydrous CaCl 2 or P 2O 5, they decreased. The process is reversible and can be interpreted as a sorption/ desorption of H 2O vapours. The concentration of SO 4 2− ions in the annealed films as determined by spectrophotometric titration, was 76–200 μg cm −2. By X-ray diffraction analysis, an increase of the average crystallite size and a decrease of the microstrains were observed.