Characterization of VO2 films grown by magnetron sputtering

Vanadium dioxide (VO₂) which is a transition metal compound demonstrates metal insulator transition (MIT) property. The transition carries out at nearly 68 °C ¹. VO₂ exhibits insulator phase with monoclinic crystal structure at low temperatures below the transition, while metallic phase with tetragonal crystal structure at high temperatures above the transition ². Electrical resistivity of VO₂ at MIT changes by a factor of 10⁴. VO₂ has high potential for the applications in microelectronic devices. It is used not only for FET applications, but also for other devices including nonvolatile resistive memories, optical sensors and termochromic smart window. In this work, c-cut sapphire (Al2O3) and soda lime glass (SLG) were used as substrate. 60 nm thick VO2 films were deposited in vacuum chamber by dc reactive magnetron sputtering technique. The substrates were rotated for the purpose of homogeneous film growth and kept at 500 °C during deposition. The grown films were characterized using various techniques which are X-ray diffraction (XRD) for identifying atomic and molecular crystal structure, Raman microscopy for observing vibrational and rotational modes,X-ray photoelectron spectroscopy (XPS) for chemical analysis and elemental composition,and scanning electron microscopy (SEM) to determine surface topography and composition of the films. Moreover, post annealing processes at different temperatureswere done to analyse the resistance of VO2 films grown with different O₂/Ar gas ratios.