Delicate tuning of epitaxial VO2 films for ultra-sharp electrical and intense IR optical switching properties

Epitaxial VO2 films on r-sapphire substrates with ideal composition, dense structure and superior functional properties were obtained by water-assisted MOCVD from vanadyl hexafluoroacetylacetonate followed by the annealing under optimized conditions. The obtained films exhibit both intense optical switch properties in IR region and unique MIT characteristics: change in resistance by 4.6 orders in the temperature range 40–80 °C, hysteresis width less 0.7 °C and transition width 1.5 °C. The proposed synthetic approach opens new opportunities to fabricate highly sensitive and ultrafast switches for optical, electronic and biomedical devices. •Highly oriented (100)VO2 films grown on r-Al2O3 at 350 °C using MOCVD based on reaction between VO(hfa)2 and water vapors.•Manipulation with MIT of VO2 by annealing under controlling oxygen pressure in ranges of 15–120 min and 550–650 °C.•Record MIT parameters for VO2 films: change in resistance by 4.6 hysteresis width less 0.7 °C and transition width 1.5 °C.•Ultra-sharp electrical and optical MIT (IR reflectance) for epitaxial VO2 films.•The new model of VO2 recrystallization at temperatures below 600 °C based on melting of VxO2x+1 impurities.