High-quality deposition of vanadium dioxide (VO2) films using magnetron sputtering

International audienceVanadium dioxide (VO2) has attracted an increased attention due to its ability to undergo a reversible metal to insulator transition (MIT) which can be thermally induced at a temperature of 340K or, more interesting, via optical or electrical excitations. The MIT is inducing drastic changes in the material's optical and electrical properties which have made VO2 an interesting material for integration in different electrical and optical devices (high-speed optical and electrical switches, field-effect transistors, oscillators…). The electrical and optical performances of the obtained films are strongly correlated with the quality, grain size, degree of strain and oxidation of the material. Thus, in order to better control the electrical resistivity or optical transmission changes during MIT (hysteresis and transition width, transition temperature), a good understanding of the film's growth mechanism is needed. We have investigated the structural, morphological and electrical characteristics of VO2 thin films obtained by DC magnetron sputtering of a vanadium target in Ar/O2 atmosphere, on large area substrates, up to 3". We examined the impact of the deposition and post-deposition annealing parameters on the structural and electrical properties of VO2 coatings. The films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and electrical resistivity measurements. These combined analysis results indicate that the deposition and annealing temperatures along with the oxygen partial pressure are the most important parameters in order to achieve mono oriented VO2 films with state-of-the-art amplitude resistivity changes between the two states (superior to 5 orders of magnitude)