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石墨烯是目前已知的理想二维薄膜,具有独特的能带结构,表现出优异的电学、光学特性和良好的兼容性。同时面对石墨烯的带内跃迁恰好与太赫兹频带相对应的独特优势,提出了一种石墨烯-硅复合结构对太赫兹的主动控制,并且实现对太赫兹传输的显著调制。本文主要采用太赫兹时域光谱技术对基于石墨烯复合结构进行深入的研究。实验揭示了在连续的蓝紫光泵浦条件下,复合结构太赫兹波的透射率随外加电压表现出双向大范围的变化,反射率却表现出单调的微弱变化的光谱特性。面对复合结构对太赫兹传输表现出的奇异特性,本文采用Kubo模型和肖特基结理论,指出了这一光谱变化与石墨烯和硅的电导率密切相关。
Graphene is an ideal two-dimensional film known so far, with a unique band structure, showing excellent electrical and optical properties and good compatibility. In the meantime, in face of the unique advantage that the in-band transition of graphene corresponds to the terahertz band, a graphene-silicon composite structure is proposed to control terahertz (THz) actively and achieve significant modulation of terahertz transmission. In this paper, terahertz time-domain spectroscopy is used to study the graphene-based composite structure. Experiments revealed that the terahertz wave transmissivity of the composite structure showed a bidirectional large-scale change with the applied voltage under continuous blue-violet pumping conditions, but the reflectance exhibited a monotonically weak spectral change. Facing the singularity of terahertz transmission, the Kubo model and the Schottky junction theory are used in this paper. It is pointed out that this spectral change is closely related to the conductivity of graphene and silicon.