Phase Control of Multivalent Vanadium Oxides VO x by Ion-Beam Sputter-Deposition

Vanadium-oxygen materials are of interest for various applications and fields of solid-state physics owing to the unequaled plethora of different phases. The wealth of phases and complexity of its phase diagram infer a strong sensitivity on the growth parameters for each phase. Thus, the reproducible growth of vanadium-oxide thin-films of defined phases by nonequilibrium techniques is challenging. Here, it is shown that ion-beam sputter-deposition (IBSD) is a powerful tool to reproducibly deposit defined polycrystalline vanadium oxide films by precisely controlling oxygen flux and substrate temperature in the growth process. Hence, it is demonstrated that IBSD has the potential to reliably produce binary phases (including unstable phases) from the vanadium-oxygen phase space. X-ray diffraction (XRD) and Raman spectroscopy are used to establish a map of the different crystalline phases dependent on the growth parameters. In particular, it is proved that thin-film V3O7 can be realized by IBSD and its Raman fingerprint is unambiguously identified.