Fabrication and Electrical Properties of Pure VO2 Phase Films

Abstract

We have grown VO2 thin films by laser ablation for electronic device applications. In obtaining the thin films of the pure VO2 phase, oxygen partial pressure is a critical parameter because vanadium oxides have several phases with the oxygen concentration. It is found that the pure VO2 films are epitaxially grown on Al2O3 substrate in the narrow ranges of 55-60 mTorr in an Ar+10% O2 ambient, and that the mixed phase films are synthesized when the deposition pressure slightly deviates from the optimum pressure. The (100) oriented VO2 films undergo an abrupt metal-insulator transition (MIT) with resistance change of an order of 104 at 338K. In the films of mixed phases, the small change of the resistance is observed at the same temperature. The polycrystalline films grown on SiO2/Si substrate undergo a broaden MIT of the resistance. Furthermore, the abrupt MIT and collective current motion appearing in metal are observed when the electric field is applied to the film.