Undoped and doped VO2 films grown from VO(OC3H7)3

Thin VO2-containing films have been grown on glass from vanadyl tri-isopropoxide by both chemical vapor deposition (CVD) and gel hydration. Undoped films grown by CVD were used to characterize the near-IR transmittance switching at 680C. Spectral and resistive switching are known to accompany this monoclinic-tetragonal symmetry transition. Relatively large spectral switching occurred within 0.8-2.2 μm even when resistive switching was poor, i.e. less than twofold. The largest resistive switching observed was about 103-fold, which is similar to the best reported elsewhere for VO2 films prepared on glass in other ways. In the case of gel preparation, the films were doped with tungsten, molybdenum or niobium to demonstrate shifting of the transition below 680C. The depression achieved with these films is qualitatively consistent with the conclusions of other researchers that are based on doped VO2 crystals and powders. By comparison with undoped CVD films, however, there is no indication that doping has any unusual effect on IR switching. (Auth.)