Annealing characteristics of the vanadium oxide films prepared by modified ion beam enhanced deposition

Different annealing conditions were adopted to anneal the vanadium oxide films prepared by modified ion beam enhanced deposition (IBED) method. An X-ray diffraction (XRD) was used to analyze the orientation of the IBED films and the resistance was tested with temperature change to measure the temperature coefficient of resistance (TCR). Experiments indicated that there existed a critical temperature for crystallization of VO2, which changed with the different deposition conditions of the IBED method. It is very difficult to obtain VO2 structure if the annealing temperature was lower than the critical temperature. If the temperature is much higher than the critical temperature or annealing time is too long, the valence of vanadium in VO2 film will easily reduce from four to low value. The TCR of the IBED VO2 polycrystalline films annealed in appropriate condition could reach higher than 4%/K.