Photo-induced insulator-metal transition of silicon-based VO2 nanofilm by THz time domain spectroscopy

Abstract

The photo-induced insulator-metal transition for silicon-based VO2 nanofilm is studied by THz time-domain spectroscopy (THz-TDS). Obvious variations of THz ray transmittance are observed before and after the CW laser beam exciting, and the conductivity of metallic-phased VO2 film in the THz region is calculated in the thin film approximation. According to the measured results, the metallic-phased VO2 film is characterized equivalently with Drude’s model, and complex conductivity, dielectric function and refractive index are acquired by the model. As an examination on the equivalent Drude model, numerical simulation based on the finite integral method in time domain is carried out. The results show that they are in good agreement with the experimental results. This work provides a reference for the study on phase transition of VO2 nanofilm and its application in the THz region.

Photo-induced high modulation depth terahertz modulator based on VOx–Si–VOxhybrid structure

“…Wang et al simulated the process of THz pulse penetrating the silicon based vanadium dioxide film by using the FDTD method. Their results show good agreement with that from the Drude model [26]. Meanwhile, equation (5) shows that the load impedance is proportional to the relative transmission T m .…”

“…The THz wave attenuation caused by pumping the VO 2 film with lower laser power is mainly due to the change of the conductivity of vanadium oxide [26]. Based on the Drude model, the conductivity can be written as…”

The Stability Study on Vanadium Dioxide

“…Moreover, the phase transition in VO 2 thin films can be triggered very fast (even to femtosecond scale) [4,5,6] . All these dramatic characteristics make VO 2 a promising material to various technological applications, such as electrical switches, smart windows, terahertz nano-antennas, optical components and memory metamaterials, and so on [3][4][5][6][7][8][9][10][11][12][13][14] . Extraordinary properties make VO 2 very attractive for versatile potential applications, but the insulator-metal phase transition may be very easily affected [15][16][17] .…”