College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China.
ACS Appl Mater Interfaces. 2011 Sep;3(9):3523-7. doi: 10.1021/am200734k. Epub 2011 Sep 2.
VO(2) films were fabricated on high-purity single-crystalline silicon substrate by the sol-gel method, followed by rapid annealing. The composition and microstructure of the films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The results indicated a polycrystalline nature with high crystallinity and compact nanostructure for the films, and the concentration of +4 valence vanadium is 79.85%. Correlated with these, a giant transmission modulation ratio about 81% of the film was observed by terahertz time domain spectroscopy. The experimentally observed transmission characteristics were reproduced approximately, by a simulation at different conductivities across the phase transition. According to the effective-medium theory, we assumed that it is important to increase the concentration of +4 valence vanadium oxide phases and improve the compactness of the VO(2) films for giant phase transition properties. The sol-gel-derived VO(2) films with giant phase transition properties at terahertz range, and the study on their composition and microstructure, provide considerable insight into the fabrication of VO(2) films for the application in THz modulation devices.
通过溶胶-凝胶法在高纯度单晶硅衬底上制备 VO(2) 薄膜，然后进行快速退火。通过 X 射线光电子能谱（XPS）、X 射线衍射（XRD）、场发射扫描电子显微镜（FE-SEM）和原子力显微镜（AFM）研究了薄膜的组成和微观结构。结果表明，薄膜具有多晶特性，结晶度高，纳米结构致密，+4 价钒的浓度为 79.85%。相关的，通过太赫兹时域光谱观察到薄膜的传输调制比约为 81%。通过在不同的相变点处的电导率的模拟，大约再现了实验观察到的传输特性。根据有效介质理论，我们假设增加+4 价氧化钒相的浓度并提高 VO(2) 薄膜的致密性对于获得巨大的相变性能是很重要的。具有太赫兹波段巨大相变性能的溶胶-凝胶衍生 VO(2) 薄膜及其组成和微观结构的研究，为在太赫兹调制器件中应用 VO(2) 薄膜的制备提供了有价值的见解。
