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We design and fabricate a totally encapsulated VO/Au/VO composite structure which is aimed to improve the tunability of the localized surface plasmon resonance (LSPR) peak. In this work, the structure will ensure all the Au NPs' resonant electric field area is filled with VO. The modulation range of the totally encapsulated structure is larger than that of the semi-coated structure. To further improve the modulation range, we also explore the VO thickness dependence of the structure's LSPR modulation. With the increase of the top layer VO thin film thickness, the modulation range becomes larger. When the thickness is about 80 nm, the absorption peak achieves a largest shift of 112 nm. FDTD solution and equivalent model of series capacitor are used to explain the phenomenon. These results will contribute to the area of metamaterial electromagnetic wave absorber and other fields.

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Rapid thermal oxidation of sputtering power dependent vanadium thin films for VO 2 thin films preparation is investigated. Metallic vanadium thin films are deposited by direct current magnetron sputtering at different sputtering power. They are characterized by the atomic force microscope (AFM) and the field emission-scanning electron microscope (FE-SEM). In our experiment, we increase the sputtering power while reducing the sputtering time to maintain the same thickness of the film. In this process, the particle size of metallic vanadium increases. The vanadium thin films are oxidized at the same annealing conditions by rapid thermal annealing. X-ray diffraction (XRD) results indicate there is polycrystalline VO 2 in oxidation products of the metallic vanadium with large average particle radius. Surface morphology and metal-to-insulator transition (MIT) properties of VO 2 thin films are characterized. When average particle radius of the metallic vanadium is 8.78 nm, the VO 2 thin film has the largest particles and maximum phase transition magnitude. These results reveal the relationship of sputtering power and the particle size of vanadium thin films, and illustrate the effect of the particle size of vanadium thin films on VO 2 thin films preparation through the oxide growth rate law for the oxidation of spherical particles.