Direct Measurement of Terahertz Conductivity in a Gated Monolayer Semiconductor

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Abstract
Two-dimensional semiconductors and their moiré 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 a 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.
Funding Information
  • University of California Berkeley
  • NIH Office of the Director (S10OD034382)
  • Division of Materials Sciences and Engineering (DE-AC02-05-CH11231)
  • Ministry of Education, Culture, Sports, Science and Technology
  • Japan Society for the Promotion of Science (21H05233, 23H02052)
  • Division of Materials Research (2311205)