Growth of Polycrystalline CdS Films by Low-Pressure Metalorganic Chemical Vapor Deposition

Polycrystalline CdS films were grown at temperatures between 50 and 400°C by reacting DMCd and H2S, and the electrical and optical properties of the films were examined. It was found that the films show a preferential orientation to (0001) direction and that their electrical properties are remarkably influenced by the sulphur vacancy. The resistivity of undoped films ranged from 103 to 107 Ω·cm and became maximum at about 250–300°C. Furthermore, the resistivity of the films could be successfully reduced to about 10-1 Ω·cm by doping Al as a donor impurity.