Influence of bias voltage on microstructure and phase transition properties of VO2 thin film synthesized by HiPIMS

VO2 thin films were prepared on quartz glass substrates by using high power impulse magnetron sputtering with different pulsed bias voltages. X-ray diffraction patterns revealed that all as-deposited films were polycrystalline monoclinic VO2 and the preferred crystalline orientation of the as-deposited films varied with the magnitude of the bias voltage. Scanning electron microscopy images exhibited that the crystalline size of the VO2 thin films reduced with the magnitude of the bias voltage. X-ray photoelectron spectroscopy results revealed that oxygen vacancies were formed in all films and their quantities were similar. UV-visible-near IR spectra of the VO2 thin films at different temperatures confirmed that all films possessed typical metal-insulator transition properties. Four point probes resistivity results exhibited that the phase transition temperature was reduced from 54 to 31.5 degrees C when the magnitude of the bias voltage was increased from -50 to -250 V. (C) 2016 Elsevier B.V. All rights reserved.