Thin films of V2O5 and β-Cu
V2O5 have been grown by MOCVD using VO(OiPr)3 and Cu(tmhd)2 (tmhd = tetramethylheptanedionato) as precursor molecules. Films were grown on chips of Si3N4 coated silicon wafers in a cold wall reactor using a H.F. heater. A mixture of helium and oxygen was used as a reactive carrier gas, and depositions were performed at low pressure. The films were examined by SEM, characterized by XRD, and analyzed by EDS and EMPA techniques. All the films proved to be carbon free.
For V2O5, the substrate temperature was varied from 450 to 630°C. The films are highly caxis oriented for both ends of the temperature range, and less oriented for intermediate temperatures. For 630°C, the XRD pattern consists almost entirely of reflections (001) and (002).
V2O5, the substrate temperature was varied from 450°C to 650°C. Pure β-phase films with x varying from 0.25 to 0.55 have been obtained above 500°C, by using well chosen gas phase composition. Morphology and texture depend dramatically on the temperature. The most oriented films exhibit a strong anisotropy of electrical surface conductivity.