Abstract-Synthesis and terahertz transmission properties of nano-porous vanadium dioxide films

http://iopscience.iop.org/0022-3727/45/38/385302

Vanadium dioxide (VO₂) films were prepared by the sol–gel method on high-purity silicon substrates, in which cetyltrimethyl ammonium bromide (CTAB) was used as a functional additive to form nano-porous structure in the VO₂ films. The morphology, crystalline structure and stoichiometry of the films were investigated by field emission scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. Furthermore, the effects of nano-scaled grain size and pores on the THz transmission properties across the phase transition in the VO₂ films were studied. The results indicated that the film modified with CTAB can form a nano-porous VO₂ structure with a uniform grain size of about 30 nm. The nano-porous VO₂ film exhibited significantly broader hysteresis loops and a slight decrease in THz transmission reduction across the phase transition, compared with the common film without a nano-porous structure. A tentative interpretation is given for these phenomena.