A new electrochemical technique for deposition of Chevrel-phase compound M(y)Mo6X8 thin films

Chevrel-phase Cu(y)Mo6X8 thin films have been deposited cathodically under galvanostatic conditions from an aqueous electrolyte bath (pH greater than 9) containing solutions of CuCl, MoCl, Na2SeSO3, and Nh4OH. The films have been grown under different deposition conditions by varying (1) the deposition current density and (2) the electrolyte bath composition. Energy-dispersive analysis of X-rays and X-ray diffraction studies showed that the as-deposited films were non-stoichiometric with rhombohedral structure and contained an additional phase of Cu(2-x)Se along with Chevrel phases. The binary phase, however, disappeared on annealing at 300 C for 5 min. The optical absorption studies showed that the bandgap of annealed films varies between 0.8 and 1.1 eV and depends on the S/Se atomic ratio. The resistivity of the films varies from 0.2 to 0.3 Ohm cm.