Properties in vanadium dioxide thin film synthesized from V2O5 annealed in H2/Ar ambience

Abstract

Owning to its sharp metal-insulator transition at ～340 K, VO2 is becoming an attractive candidate for the electrical and optical material. Here we report on the fabrication and characterization of VO2 thin film obtained from the V2O5 thin film annealed in Ar/H2 ambience. V2O5 thin film is fabricated by using the pulsed laser deposition system on the R-sapphire substrate under several different conditions by varying the substrate temperature and the pressure of the growth atmosphere to optimize the growth condition. Then we carry out the annealing treatment on the V2O5 thin film in different annealing conditions. The VO2 thin films are characterized using X-ray diffraction, X-ray photoelectron spectroscopy and R-T measurement. When annealed in a temperature range of 500–525 ℃ for 3 h in H2(5%)/Ar ambience, the V2O5 thin film can be converted into the mixed-structures of metastable monoclinic structure (B) and the monoclinic rutile structure (M) which is responsible for the phase-change property. And under the same conditions, when the annealing time reaches 4.5 h, the pure VO2(B) is obtained. Further we anneal the VO2(B) in pure Ar ambience and tentatively realize the resistivity reduced by nearly four orders with the temperature increasing from 25 ℃ to 105 ℃. The transition temperature is nearly 350 K. And the transition between VO2 (B) and VO2 (M) is realized.