Tuning layer-hybridized moiré excitons by the quantum-confined Stark effect

Yanhao Tang; Jie Gu; Song Liu; Kenji Watanabe; Takashi Taniguchi; James Hone; Kin Fai Mak; Jie Shan

doi:10.1038/s41565-020-00783-2

Tuning layer-hybridized moiré excitons by the quantum-confined Stark effect

Nat Nanotechnol. 2021 Jan;16(1):52-57. doi: 10.1038/s41565-020-00783-2. Epub 2020 Nov 2.

Authors

Yanhao Tang¹, Jie Gu¹, Song Liu², Kenji Watanabe³, Takashi Taniguchi³, James Hone², Kin Fai Mak^{4

5

6}, Jie Shan^{7

8

9}

Affiliations

¹ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
² Department of Mechanical Engineering, Columbia University, New York, NY, USA.
³ National Institute for Materials Science, Tsukuba, Japan.
⁴ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. kinfai.mak@cornell.edu.
⁵ Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA. kinfai.mak@cornell.edu.
⁶ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA. kinfai.mak@cornell.edu.
⁷ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. jie.shan@cornell.edu.
⁸ Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA. jie.shan@cornell.edu.
⁹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA. jie.shan@cornell.edu.

PMID: 33139934
DOI: 10.1038/s41565-020-00783-2

Abstract

Moiré superlattices offer an unprecedented opportunity for tailoring interactions between quantum particles^1-11 and their coupling to electromagnetic fields^12-18. Strong superlattice potentials generate moiré minibands of excitons^16-18-bound pairs of electrons and holes that reside either in a single layer (intralayer excitons) or in two separate layers (interlayer excitons). Twist-angle-controlled interlayer electronic hybridization can also mix these two types of exciton to combine their strengths^13,19,20. Here we report the direct observation of layer-hybridized moiré excitons in angle-aligned WSe₂/WS₂ and MoSe₂/WS₂ superlattices by optical reflectance spectroscopy. These excitons manifest a hallmark signature of strong coupling in WSe₂/WS₂, that is, energy-level anticrossing and oscillator strength redistribution under a vertical electric field. They also exhibit doping-dependent renormalization and hybridization that are sensitive to the electronic correlation effects. Our findings have important implications for emerging many-body states in two-dimensional semiconductors, such as exciton condensates²¹ and Bose-Hubbard models²², and optoelectronic applications of these materials.