Nanocrystalline vanadium dioxide (VO2) thin films were prepared on glass substrates at different deposition temperatures by oxidizing sputtered vanadium films. Atomic force microscope, x-ray diffraction, and Raman scattering were employed to characterize the films. It was confirmed that low deposition temperature resulted in improving oxygen atom diffusion and VO2 nanograin growth in the thermal oxidation process. Investigation of the electrical properties revealed that the amplitude of semiconductor-metal transition and transition temperature decreased, whereas the Hall mobility and carrier concentration increased as the deposition temperature elevated. Optical investigations were carried out in the ultraviolet-visible-near-infrared region. Narrow optical band gaps were observed in these films. (c) 2010 American Vacuum Society. [DOI: 10.1116/1.3443562]