Evaluation of V_1-xCr_xO₂ Thin Films Fabricated by MOD

Abstract

Cr-doped vanadium dioxide, V_1-xCr_xO₂ (x = 0-0.20), thin films were fabricated by metal-organic decomposition. From X-ray diffraction patterns of the films at room temperature, VO₂(M₂)(201) and VO₂(M₂)(201) diffraction peaks were observed for x = 0.03-0.20, while a VO₂(M₁)(011) peak was observed for x = 0-0.01, where M₁ and M₂ represent different monoclinic structures of VO₂. Moreover, all the fabricated films showed a p-type conductivity, and the hole concentration in the films increased with increasing x. From R-T characteristics of the films at the temperature range from 20 to 90℃, abrupt resistance changes caused by the metal-insulator transition in VO₂ with a hysteresis loop were gradually suppressed with increasing x; especially x≥0.15, they were completely suppressed, since the transition temperature of the film shifted to a temperature above 140℃. Relatively flat temperature dependence of the temperature coefficients of resistance (TCR) as high as -3.9%/K in the range of 20-90℃ was obtained for the V_0.85Cr_0.15O₂ thin film. The TCR value of the film is almost same as that of a V_0.75Ti_0.25O₂ thin film, whereas a resistivity of the former at room temperature is one order lower than that of the latter.