Growth mode and texture study in vanadium dioxide thin films deposited by magnetron sputtering

Vanadium dioxide (VO2) films with thicknesses of 80, 440 and 1000 nm were deposited on glass substrates by reactive dc magnetron sputtering. The crystallization, surface morphology and structural features were studied by x-ray diffraction, atomic force microscope and scanning electron microscope. Results revealed that the structural features of VO2 films strongly depend on the film thickness. The grain size and the crystallization extent increase with the increase in film thickness. The growth of VO2 was demonstrated to be an obvious 'columnar' growth perpendicular to the surface of the glass substrate. Analyses of square resistance and its temperature dependence demonstrated that the thickness of VO2 films plays an important role in their electric properties. With increasing film thickness, the square resistance decreases, the temperature coefficient of the square resistance increases and the metal-semiconductor phase transition becomes obvious.