Vanadium Oxide Thin Films Synthesized by Reactive Ion Beam Sputter Deposition: Influence of Processing Parameters

Vanadium oxide thin films were deposited by reactive ion beam sputtering deposition onto glass substrates. The films were prepared by sputtering from a metallic vanadium target with an argon+oxygen ion beam in vacuum. Different processing conditions were evaluated with focus in obtaining monoclinic VO2(M) phase, which is known to exhibit a semiconducting-metal phase transition near room temperature. X-ray diffractometry (XRD) analyses revealed amorphous films for temperatures below 500°C. In crystalline films, the co-existence of VO2(M) with other phases was suppressed by pre-depositing a very thin metallic vanadium seeding layer which showed to promote the formation of single phase VO2(M) films. The VO2(M) films showed clearly the distinctive optical modulation behavior at the near-infrared range when going through the phase transition. The temperature dependence of sheet resistance supports the optical analyses revealing an evident semiconducting-metal behavior change up to over 2 orders of magnitude.