Some Optical and Electrical Properties of Chemically Deposited Lead Sulfide Films

The electrical and optical properties of chemically deposited lead sulfide films on plain glass, frosted glass and zinc sulfide substrates are investigated using various techniques which include noise measurements, optical transmission measurements, scanning electron microscopy, Auger spectroscopy, and electrical resistivity measurements. The noise properties of the film are a function of the substrate and the surface conditions. Mobilities of the polycrystalline films are two orders of magnitude lower than the mobilities of single crystal PbS. Impurities such as oxygen in the films play an important role in determining the optical and electrical properties of the films. Furthermore, the presence of oxygen in the film can modify the lattice structure of the crystallites in such a way that the optical band gap of the film is increased. The films are p-type. Attempts to change the carrier type of the films from p-type to n-type were unsuccessful.