Structure and Composition of Chemically Deposited Thin Films of Bismuth Sulfide and Copper Sulfide: Effect on Optical and Electrical Properties

Chemically deposited thin films of bismuth sulfide (0.13 μm) and copper sulfide (0.3 μm) and copper sulfide films deposited on bismuth sulfide have been studied so as to obtain information about their structure, composition, thermal stability, and their effect on the optical and electrical properties. The studies establish that bismuth sulfide thin films become crystalline upon air annealing near 200°C and remain stable up to 300°C. But oxygen chemisorption reduces the photo‐ and dark conductivities of the films annealed at 300°C. The studies establish that the copper sulfide films are (covellite), which is stable up to 220°C. However, films deposited on bismuth sulfide substrate films retain useful electrical and optical properties for annealing temperatures up to ∼300°C.