M-S (M=MO, W) CLUSTER COMPOUND FILMS ON COPPER SURFACES

M-S cluster compound films on copper surfaces were investigated by XPS , AES and FT-IR. The results show that Mo-S-Cu and W-S-Cu bonds had be en formed by the reaction of MoS42- and WS42-, respectively, with the Cu2O layer on a copper surface. The films are composed of the elements Mo(W), S, Cu and O. The valence of each element is +6, -2, +1 and -2, respectively. According to the AES depth profile curves, the relative atomic contents of the elements were estimated and a multimolecular l ayer structure of the films was verified. Some of the sulfur atoms had been oxidized in the outer molecular layers while MoS4 or WS2 units r emain in the inner molecular layers. The thickness of the film was fou nd to depend on the reaction time: longer times resulted in thicker fi lms. The colors of the films are probably caused by a statistical dist ribution of various layers since the films are complicated multicompon ent and multilayer systems.