Effects of oxygen in ion-beam sputter deposition of vanadium oxide

Abstract

Oxides of vanadium, 190–310 nm thick, were deposited by ion-beam sputtering of a metallic target. The ion beam consisted of an argon–oxygen mixture where the oxygen percentage was varied from 10% to 50%. Spectrophotometry was used for infrared optical characterization, while x-ray diffractometry and scanning electron microscopy were used to examine coating structure. Results show that as the oxygen fraction of the sputtering gas is increased, the crystallography evolves from a face-centered-cubic vanadium oxide to a mixed oxide phase containing VO2 in which there is a degree of preferential grain orientation. Increase of the oxygen content above 25% leads to a mixed oxide phase containing V2O5 with a structure of long, randomly oriented grains. Changes in optical reflectance and transmittance data, which accompany the structural changes, are presented and discussed.