Effect of low-valence vanadium buffer layer on the properties of vanadium oxide film

Vanadium dioxide (VO 2 ) is a promising candidate for implementing switching modulation devices due to its well-known metal-to-insulator transition (MIT). In addition, the application of VO 2 on modulation devices requires a narrow hysteresis loop width and a large phase transition amplitude, which is related to significant changes of electrical properties. In this paper, by adding a low-valence vanadium buffer layer, it is possible to increase the phase transition amplitude, reduce the loop width, and reduce the phase transition temperature. The VO 2 film deposited at a argon–oxygen ratio of 98:0.5 with a buffer layer (sputtering time: 1 min) demonstrated excellent properties: phase transition amplitude of 819 times, loop width of 10.3 °C, and phase transition temperature of 58.2 °C, which is better than that of pure VO 2 film with phase transition amplitude of 253 times, loop width of 17.8 °C, and phase transition temperature of 66 °C. As the thickness of the buffer layer increases, the phase change amplitude of the film decreases, and the width of the loop decreases. When the buffer layer was sputtered for 2 min, the loop width was only 5.4 °C, and it also maintained a high phase transition amplitude of 423 times. The enhancement of the phase transition properties of the film is related to the high crystallinity of the buffer layer film. These results indicate that the MIT characteristics of the vanadium oxide film can be adjusted by the buffer layer composition and the thickness of the buffer layer, providing an effective solution for designing a switch modulation device based on vanadium oxide film with a suitable MIT property.