Synthesis of Cu₃BiS₃ Thin Films by Heating Metal and Metal Sulfide Precursor Films under Hydrogen Sulfide

The synthesis of Cu 3 BiS 3 thin films on fused silica substrates by heating Cu−Bi metal precursor films and Cu−S−Bi metal sulfide precursor films in a H 2 S atmosphere has been investigated. We have systematically evaluated the effect of precursor composition and structure, heating temperature, heating profile, and gas composition and pressure. Phase-pure Cu 3 BiS 3 films 250−1000 nm thick were formed, with the morphology of the resulting films being highly dependent on the composition, structure, and heating profile of the precursor films. It was found that precursor composition determines the reaction pathway, and that the reaction pathway is the dominant factor in controlling the morphology of the Cu 3 BiS 3 thin film. This precursor/pathway/morphology relationship results in Cu 3 BiS 3 thin films that are discontinuous or contain hollow pockets between the film and substrate, regardless of the processing conditions employed. The electrical resistivity of these Cu 3 BiS 3 films ranged from 3−200 Ω cm.