Structural morphology and electrical transitions of V[formula omitted]O[formula omitted] thin films grown on SiO[formula omitted]/Si by high power impulse magnetron sputtering

Abstract

The study presents the synthesis of V2O3 films on thermally oxidized Si(001) substrates by reactive high power impulse magnetron sputtering. The effect of film thickness and oxygen variation were explored at fixed discharge parameters. X-ray diffraction (XRD), grazing incidence-XRD and pole scans reveal the films to be textured. The results show that for a critical thickness up to ∼ 5 nm, highly strained V2O3 films are obtained, and with increased thickness the film exhibit increased surface roughness and the formation of a granular structure arising from strain relaxation in the films. With increasing thickness the films exhibit a variation in the lattice parameters affecting their electrical characteristic i.e. metal-insulator transition (MIT). Subject to variation in O2 flow setting we observe the MIT magnitude and transition temperatures to be strongly dependent on the film stoichiometry and lattice parameters which can be fine tuned by mapping the O2 flow settings. The most dominant transition out of the studied structures was observed for those having film thickness of ∼ 36 nm with an O2 flow setting ranging from 0.8 to 0.95 sccm and displaying a low c/a lattice ratio. The MIT observed for these structures displayed a change in resistance of up to ∼ 4 decades with a total change in resistance of ∼ 7 decades.