We investigate the terahertz optical properties of VO2 (M) films synthesized hydrothermally on a c-sapphire substrate by a two-step method. The terahertz transmittance is greater than 70% for the insulating state of monoclinic VO2 films, and the average modulation depth approaches 94% for frequencies of 0.2–2.0 THz. A sample prepared using 450 °C postannealing undergoes a sharp insulator–metal transition around 61 °C at 1.5 THz with a 97% modulation depth. Furthermore, the effects of the postannealing temperature on the structure, morphology, and phase-transition properties of VO2 film/c-sapphire samples are presented. The results show that the hydrothermal synthesis of VO2 polymorphs has potential applications in the terahertz wavelength range.
Two-step hydrothermal growth of a thin film of vanadium dioxide on sapphire with large terahertz modulation depth
Note: This paper is part of the Special Topic section “Advances in Terahertz Solid-State Physics and Devices” published in Journal of Applied Physics April 21, 125(15) (2019).
Rui-ke Wang, Hai Wang, Zhi-qiang An, Jing-suo He, Cun-lin Zhang, Guo-ping Pan, Xiang Li; Two-step hydrothermal growth of a thin film of vanadium dioxide on sapphire with large terahertz modulation depth. J. Appl. Phys. 28 April 2019; 125 (16): 163104. https://doi.org/10.1063/1.5050640
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