Preparation of +4-Valent Vanadium Oxide Films via the Co-Sputtering of Mg and V₂O₅

Vanadium oxide films were deposited on a silicon substrate via co-sputtering a high-purity magnesium and vanadium pentoxide target under high vacuum at room temperature. Owing to the reducibility of the magnesium atom, the valency of vanadium was reduced from +5 to +4. When the atomic ratio of Mg to V was 1:2, X-ray diffraction (XRD) results showed that the main component in the film was MgV₂O₅. X-ray photoelectron spectroscopy (XPS) results showed that both V⁴⁺ and V²⁺ were present in the fabricated films. The crystallization of the MgV₂O₅ film was in adequate condition, as observed in the SEM profiles. The results of the temperature resistivity test showed that the film experienced a phase transition near room temperature. The hysteresis loop occurred at a temperature of approximately 0.3℃ with a temperature coefficient of resistance of −8.6%/K. The material constant of the negative temperature coefficient thermistor was approximately 6700. This discovery provides a novel method for the preparation of thermal film materials for application in uncooled focal plane detectors.