Direct measurement of terahertz conductivity in a gated monolayer semiconductor

Authors:
  • SCSu-Di Chen
    Su-Di Chen
  • QFQixin Feng
    Qixin Feng
  • WZWenyu Zhao
    Wenyu Zhao
  • RQRuishi Qi
    Ruishi Qi
  • ZZZuocheng Zhang
    Zuocheng Zhang
  • DADishan Abeysinghe
    Dishan Abeysinghe
  • CUCan Uzundal
    Can Uzundal
  • JXJingxu Xie
    Jingxu Xie
  • TTTakashi Taniguchi
    Takashi Taniguchi
  • KWKenji Watanabe
    Kenji Watanabe
  • FWFeng Wang
    Feng Wang
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Abstract
Two-dimensional semiconductors and their moir\'e superlattices have emerged as important platforms for investigating correlated electrons. However, many key properties of these systems, such as the frequency-dependent conductivity, remain experimentally inaccessible because of the mesoscopic sample size. Here we report a technique to directly measure the complex conductivity of electrostatically gated two-dimensional semiconductors in the terahertz frequency range. Applying this technique to a WSe2 monolayer encapsulated in hBN, we observe clear Drude-like response between 0.1 and 1 THz, in a density range challenging to access even in DC transport. Our work opens a new avenue for studying tunable van der Waals heterostructures using terahertz spectroscopy.