MOCVD growth and characterization of cobalt phospide thin films on InP substrates

Cobalt phosphide thin films were grown by MOCVD (Metal-Organic Chemical Vapor Deposition) in H2 atmospheres on (001) InP substrates using bis(eta5-methylcyclopentadienyl)Co(II) (Co(CpMe)2) and phophine (PH3) precursors at 550°C. Film microstructure, composition and morphology were investigated in detail by XRD (X-ray Diffraction), XPS (X-ray Photoelectron Spectroscopy) and AFM (Atomic Force Microscopy). Films were crystalline and consisted mainly of the orthorhombic CoP phase in agreement with XPS measurements that indicate an oxidation state (III) for Co. The coatings were highly textured with (202), (103) CoP crystal planes parallel to the substrate surface and had root mean square surface roughness in the 4-60 Å range, increasing with Co-H2 flow rate, deposition time and thickness. Cobalt and In intermixing is investigated by XPS depth profiles.