Effect of Deposition Time on the Optical Characteristics of Chemically Deposited Nanostructure PbS Thin Films

PbS thin films are good materials for antireflection coatings and for solar thermal applications in flat-plat collectors, house heating for solar chick brooding, etc. Nanocrystalline PbS thin films were deposited on glass substrates with various deposition times using chemical bath deposition technique. The study was carried out for thicknesses in the range (500-660 nm). The crystalline size of these films was studied by atomic force microscope AFM. A dense surface composed of multilayered grains of films was obtained with the crystal size around 37.67 nm. The optical properties of these films have been studied and show that PbS thin films have allowed direct transition and the values of energy gap varied between (1.88-1.55 eV) with increasing film thickness, The large optical band gap in the films is attributed to the quantum coefficient effect. Influences of thermal treatments under various annealing temperatures on the optical properties for some deposition films were studied.