MINERAL PRECURSOR FOR CHEMICAL VAPOR-DEPOSITION OF RH METALLIC-FILMS

Di-mu-chloro-tetrakis(trifluorophosphine)dirhodium(I) ((PF3)2RhCl)2, was synthesized by using the method of Bennett and Patmore, and was purified twice by sublimation. The decomposition reaction of the complex studied by Fourier transform IR spectroscopy in the vapor phase showed that no volatile species except the complex and PF3 were present in the gas phase. We used this mineral precursor to obtain metallic Rh films by chemical vapor deposition under very mild conditions (T<200-degrees-C, P=3-10 Torr) on Pyrex glass slides or NaCl substrates. The smooth Rh films obtained, with a mirror-like aspect, have been characterized by X-ray diffraction (indicating a crystalline nature, f.c.c., F(m3mBAR) with a=3.806(2) angstrom), transmission electron microscopy (800 angstrom x 50 angstrom x 50 angstrom single crystals are present) and X-ray photo-electron spectroscopy. Neither P nor F atoms could be detected, but a significative amount of Cl atoms was present in the films identified as RhCl3.