Structure and electrical properties of selectively chemically vapor deposited vanadium oxide films from Vanadium tri-i-propoxy oxide vapors

Vanadium oxide films were chemically vapor deposited (CVD) on oxidized Si substrates covered with patterned Cu films using Vanadium tri-i-propoxy oxide (OV(OC3H7)3) vapors. It was shown that at atmospheric pressure and at temperatures varying between 135 and 350 °C deposition was selectively occurring on the patterned Cu films only and not on the silicon oxide, which covered the Si substrate. The dependence of the selectivity on the composition of the gas phase was investigated and it was shown that low precursor concentrations enhance selectivity. X-ray diffraction measurements have shown that the deposited films were composed of a mixture of vanadium oxides; the composition dependent on the deposition temperature. At temperatures up to 150 °C films were mostly composed by monoclinic VO2. At higher temperatures other peaks corresponding to various vanadium oxides were also observed. The well-known metal-insulator transition was observed near 70 °C for films mostly composed by monoclinic VO2. Films deposited at 200 and 300 °C exhibited two transitions one near 47 and the other near 65 °C possibly related to the presence of V6O11, or of important stresses in them.