沉积氧压对二氧化钒薄膜结构、光电性能及其MIT相变特性的影响研究

The Influence of Oxygen Pressure on the Structure, Optoelectronic Properties, and MIT Characters of VO2 Thin Films

摘要: 本工作中我们采用脉冲激光沉积法，以金属钒靶作为烧蚀靶材、高纯氧气作为反应气体，通过改变薄膜生长时的氧压，在TiO₂ (110)衬底上制备VO₂薄膜。利用X射线衍射仪、X射线光电子能谱分析仪、紫外-可见-近红外光谱测试仪、四探针测试仪系统测试并研究了薄膜生长氧压对VO₂薄膜的结构、成分、光学性能及金属-绝缘体相变特性的影响。实验结果表明：不同氧压下制备的VO₂薄膜(011)晶面X射线衍射摇摆曲线半高宽都很小(在0.12˚~0.27˚范围)，表明薄膜的面外取向度很高；当氧压为6.5 Pa时，制备的VO₂薄膜摇摆曲线半高宽最小(0.116˚)，相变前后薄膜对太阳能调制最大、其电阻开关比达到4个数量级，薄膜相变温度接近63℃，金属-绝缘体转变特性显著。

Abstract: Vanadium dioxide (VO₂) epitaxial films were grown on TiO₂ (110) substrates with various O₂ pressures by pulsed laser deposition using a metal vanadium as target and high-purity O₂ as reac-tion gas. The growth experiments were carried out at a fixed substrate temperature of 600˚C and different O₂ pressures. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible-near-infrared spectrophotometer (UV-VIS-NIR) and four-probe method were used to characterize the films. The XRD rocking curve half widths at (011)-plane of the VO₂ films deposited at various oxygen pressures are all very small, in the range of 0.12˚ - 0.27˚, indicating a very good out-of-plane atomic ordering of the films. It was revealed that 6.5 Pa was the optimum oxygen pressure for the growth of high-quality VO₂ films, which exhibit a XRD rocking curve half width as small as 0.116˚, the most effective modulation to solar energy in the visible-near-infrared region, and almost four orders of magnitude change in resistance, i.e., an obvious metal-insulator transition character at a temperature around 63˚C.