Deposition of thin films of cobalt oxides by MOCVD

Abstract

The Co(hfa)₂·2H₂O (hfa = CF₃C(O)CHC(O)CF₃) precursor was used in MOCVD experiments to deposit cobalt oxides, on optically transparent SiO₂ substrates. CoO and Co₃O₄ films have been obtained depending on the adopted deposition conditions. XRD measurements provided evidence that CoO consists of cubic, (100) oriented crystals, whilst Co₃O₄ films are only partially oriented along the (311) direction. Mean crystallite sizes were evaluated from the XRD line broadening and the band-gap for Co₃O₄ was determined from the optically induced transitions. Both optical spectra and resistivity measurements of Co₃O₄ thin films showed that they are semi-conducting. The surface structure of the films was investigated by XPS.