硅基VO_2纳米薄膜光致绝缘体—金属相变的THz时域频谱研究

Photo-induced insulator-metal transition of silicon-based VO_2 nanofilm by THz time domain spectroscopy

利用THz时域频谱技术(THz-TDS)研究了硅基二氧化钒(VO2)纳米薄膜的光致绝缘体—金属相变特性.在连续光激发下前后,观察到了非常明显的THz透过率变化,并通过薄膜近似计算出了THz波段金属态VO2薄膜的电导率.根据实验结果建立了金属态VO2薄膜的等效Drude模型,得到了复电导率,复电容率以及复折射率等相关的基本参数,并通过基于时域有限积分法模拟了THz波穿透硅基金属态VO2薄膜的过程,验证了所建立的模型的正确性,为研究VO2薄膜的相变特性以及VO2薄膜在THz波段的应用提供了参考.

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.