Dynamic resistance characteristic of Vanadium oxide thin film

• Main Authors: Chia-Hua Lin, 林佳樺
• Other Authors: Cheng-Yi Liu
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/bws628

博士 === 國立中央大學 === 化學工程與材料工程學系 === 107 === Abstract In this study, dynamic resistance mechanism and characteristics of vanadium oxide thin films are discussed. At first, discusses the conduction mechanism of vanadium oxide thin film at room temperatures. According to X-ray photoelectron spectroscopy analysis, the vanadium oxide thin film has the highest V5+ ion concentration after annealing temperature at 500 oC. The V5+ ion for the V4+ ion produces free electrons and has n-type characteristic, thereby increasing the carrier concentration of the vanadium oxide film. So the vanadium oxide thin film has the characteristics of a transparent conductive film. Secondly, propose a novel dynamic resistance mechanism. The temperature sensitive property of vanadium oxide thin film was manipulated to form. The remarkable dynamic resistance characteristics can also observe in this vanadium oxide thin film. But there is no current mechanism can be used to explain the phenomenon. The experimental results show that the vanadium oxide thin film changes at two orders of magnitude at 67 °C, which is the phenomenon of dynamic resistance transition. Annealing temperature at 500 °C of vanadium oxide thin film can even have a significant dynamic resistance transition at 50 °C. Since the vanadium oxide thin film prepared by sputtering in an oxygen environment generates vanadium ions of different valence states, V5+ is measured by X-ray photoelectron spectroscopy analysis. The proportion of ions in the vanadium oxide thin film is proportional to the critical temperature change of the resistance transition. When theV5+-V4+ substitution, the V5+ ion bond is shorter than the V4+ ion bond and changes to the V at the center of the lattice. The spacing between the oxygen ligands on the energy band causes the energy gap to decrease, which in turn reduces the change in the critical temperature of the resistance transition. Therefore, the valence ratio and bond length are the key properties that determine the dynamic resistance characteristics.