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Preparation, Microstructure, and Characterization of Vanadium Oxide Thin Films

Author: WeiXiongBang
Tutor: WuZhiMing
School: University of Electronic Science and Technology
Course: Optical Engineering
Keywords: Vanadium oxide thin films DC magnetron sputtering Sputtering voltage Square resistance The square resistance temperature coefficient Thermal characteristics
CLC: O484.1
Type: PhD thesis
Year: 2008
Downloads: 912
Quote: 2
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Abstract


Vanadium oxide, generally in the form of a mixed-valence exist, common vanadium oxide having a phase transition metal - semiconductor conversion characteristics. Vanadium oxide films have good thermal properties, there is a vast potential for the development of applications in infrared detection and thermal imaging. Vanadium oxide film, the papers as the research object, using DC magnetron sputtering vanadium oxide thermal film, vanadium oxide film preparation, micro-structure, and its characteristics. Experimental process, in addition to the full use of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electric microscopy (SEM), atomic force microscopy (AFM) and other technology on the film of the microscopic structure and chemical characteristics of characterization, the focus of research of vanadium oxide films of square resistance as well as the square resistance changes with temperature characteristics, the thermal performance of the film. Addition of vanadium oxide film refractive index and extinction coefficient were also discussed. The thesis includes the following six aspects: (1) the microscopic structure of vanadium oxide films important factor affecting the film properties. Firstly, the use of a variety of analytical tools such as XPS, XRD, SEM, AFM, and a more detailed analysis of the film composition, valence state, and thin-film crystalline morphology, to experimental DC reactive magnetron sputtering understand the microscopic characteristics of the preparation of vanadium oxide film, which helps determine the vanadium oxide film growth process optimization. (2) optimization of the vanadium oxide film growth process, the paper first studied the DC reactive magnetron sputtering process of vanadium oxide films of different working gas (Ar) flow, different reaction gas (O 2 ) traffic, as well as different proportions of Ar / O 2 mixed gas under the conditions of film deposition rate and sputtering voltage changes, which proposed a new monitoring vanadium oxide film growth, the control performance of vanadium oxide films method - the sputtering voltage control method. The sputtering voltage control, monitoring sputtering voltage changes, the timely adjustment of the gas flow in the sputtering process, can effectively improve the repeatability and controllability of the film preparation process stability and reproducibility of the film properties has an important role. The use of this method in different sputtering voltage of vanadium oxide films were prepared, analyzed and compared with the performance of these films. When the the sputtering voltage selection in the (304 ~ 318) V, the film-side resistance can be controlled in (30 to 150) kΩ / □, the temperature coefficient of the film square resistance -4% / ° C to -5% / ° C, the growth of vanadium oxide films of the corresponding O / V ratio of 1.91 to 2.13. (3) the growth pattern and texture of the vanadium oxide film on the Si substrate, a glass substrate, Si 3 N 4 / Si substrate substrate research. Experimental results show that the growth mode of the vanadium oxide growth on different substrates and texture there is a big difference. Si 3 N 4 / Si vanadium oxide film grain grown on small, relatively flat film; relatively coarse grain on the glass substrate and the Si substrate , the columnar growth of the film is more obvious. Vanadium oxide film thickness adjustment will significantly change the film grain size; grain size variation of the thickness of the film and the film will result in a large change of the thin film electrical properties. Grown on different substrates 80nm, 440nm, 1000nm thick vanadium oxide film study found that the grain size of the films increased significantly with increasing film thickness; vanadium dioxide film grain grown on different substrates are presented a more rules \thickness and film grain increases, the film semiconductor - metal phase transition is also becoming more and more obvious. The experiment shows that the substrate is one of the important factors of vanadium oxide film microstructure and properties. (4), vanadium oxide films of different thickness, and further study of the optical, electrical properties of the film, the film thickness on the refractive index and extinction coefficient of the film have a greater impact. Preisach theoretical model of VO 2 film asymmetrical thermal hysteresis loop analysis to determine the changes in vanadium oxide film resistance plus temperature and temperature changes in grain volume is closely related to . (5) Try using DC magnetron sputtering in pure argon atmosphere V 2 O 5 target deposition of vanadium oxide films. Film deposition subsequent high vacuum high-temperature annealing. Phase analysis by XRD of the crystalline phase was analyzed, the results that have VO 2 crystal plane orientation of the film after the annealing treatment and before the annealing treatment, the film XPS composition analysis proved XRD results. XRD analysis of the thin-film and film side barrier characteristics of the test showed that the resulting film is a typical VO 2 (B) film. On this basis, the use of thin film grain boundary scattering theory, the effective regulation and control by changing the film thickness and the grain size of the temperature coefficient of the square resistance of the film and the side barrier. (6) Try using the first DC magnetron sputtering deposition of vanadium film its oxidation heat treatment preparation of vanadium oxide films, using this method, appropriate oxidation treatment can be optimized square resistance of the film to improve the film the square resistance temperature coefficient , processed vanadium oxide film the square resistance temperature coefficient of -2% / ℃; proportion of the film valence vanadium and vanadium-oxygen ratio is obtained by adjusting the annealing conditions improve. Through the above study, vanadium oxide films prepared micro-structure, and its performance has been further knowledge and understanding of a more useful basis for the application of vanadium oxide films do research work.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Thin Film Physics > Film growth,structure and epitaxy
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