Cobalt phosphide thin films were grown by metal-organic chemical vapor deposition (MOCVD) in H-2 atmospheres on InP(001) substrates using bis(eta-methylcyclopentadienyl)Co(II) [Co(Cp-Me)(2)] and phophine (PH3) precursors at 550 degreesC. Film microstructure, composition, and morphology were investigated in detail by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Rutherford backscattering (RBS), and atomic force microscopy. Films were crystalline and consisted mainly of the orthorhombic CoP phase and some amount of the CoP2 phase. XPS measurements indicate an oxidation state (III) for Co, while the P/Co ratio was found by RBS to lie in the range 1-2. The coatings were highly textured with (202), (103) CoP, and (-311) CoP2 crystal planes parallel to the substrate surface. The root mean square surface roughness was below 10 Angstrom for thicknesses smaller than 20 nm and increased to a maxiumum of 70 Angstrom for a 35 nm thick film. Cobalt and In intermixing was investigated by XPS depth profiles. (C) 2004 The Electrochemical Society.