CaltechAUTHORS
Published April 2021 | Version Submitted + Supplemental Material
Journal Article Open

Excitons in a reconstructed moiré potential in twisted WSe₂/WSe₂ homobilayers

Creators

  • 1. ROR icon Harvard University
  • 2. ROR icon Imec
  • 3. ROR icon California Institute of Technology
  • 4. ROR icon University of California, Irvine
  • 5. ROR icon National Institute for Materials Science

Abstract

Moiré superlattices in twisted van der Waals materials have recently emerged as a promising platform for engineering electronic and optical properties. A major obstacle to fully understanding these systems and harnessing their potential is the limited ability to correlate direct imaging of the moiré structure with optical and electronic properties. Here we develop a secondary electron microscope technique to directly image stacking domains in fully functional van der Waals heterostructure devices. After demonstrating the imaging of AB/BA and ABA/ABC domains in multilayer graphene, we employ this technique to investigate reconstructed moiré patterns in twisted WSe₂/WSe₂ bilayers and directly correlate the increasing moiré periodicity with the emergence of two distinct exciton species in photoluminescence measurements. These states can be tuned individually through electrostatic gating and feature different valley coherence properties. We attribute our observations to the formation of an array of two intralayer exciton species that reside in alternating locations in the superlattice, and open up new avenues to realize tunable exciton arrays in twisted van der Waals heterostructures, with applications in quantum optoelectronics and explorations of novel many-body systems.

Additional Information

© 2020 Nature Publishing Group. Received 12 February 2020; Accepted 11 November 2020; Published 04 January 2021. We thank B. Urbaszek, R. Bekenstein and L. Ju for helpful discussions. We acknowledge support from the DoD Vannevar Bush Faculty Fellowship (N00014-16-1-2825 for H.P. and N00014-18-1-2877 for P.K.), NSF (PHY-1506284 for H.P. and M.D.L.), NSF CUA (PHY-1125846 for H.P. and M.D.L.), AFOSR MURI (FA9550-17-1-0002) and ARL (W911NF1520067) for H.P. and M.D.L., the Gordon and Betty Moore Foundation (GBMF4543 for P.K.), ONR MURI (N00014-15-1-2761 for P.K.) and Samsung Electronics (for P.K. and H.P.). All the fabrication was performed at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF award 1541959. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, and the CREST (JPMJCR15F3), JST. A.S. acknowledges support from the Fannie and John Hertz Foundation and the Paul & Daisy Soros Fellowships for New Americans. Data availability: All data needed to evaluate the conclusions are presented in the article and the Supplementary Information. Author Contributions: T.I.A., G.S., A.S., K.D.G., H.P. and M.D.L. conceived the project. T.I.A., G.S., A.S. and K.D.G. designed and performed the experiments, analysed the data and wrote the manuscript with extensive input from the other authors. Y.Z. and J.S. assisted with the optical measurements. T.I.A., G.S., J.S., Y.Z., L.A.J. and A.Y.J. fabricated the samples. A.S. and K.D.G. performed the SEM imaging. T.I.A., G.S., A.S., K.D.G, D.S.W. and D.B. developed the theoretical model. H.H. grew the TMD crystals. T.T. and K.W. grew the hBN crystals. P.K., H.P. and M.D.L. supervised the project. The authors declare no competing interests.

Attached Files

Submitted - 1912.06955.pdf

Supplemental Material - 41563_2020_873_MOESM1_ESM.pdf

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1912.06955.pdf

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Additional details

Additional titles

Alternative title
Excitons in a reconstructed moiré potential in twisted WSe2/WSe2 homobilayers
Alternative title
Moiré Excitons Correlated with Superlattice Structure in Twisted WSe2/WSe2 Homobilayers
Alternative title
Moiré Excitons Correlated with Superlattice Structure in Twisted WSe₂/WSe₂ Homobilayers

Identifiers

Eprint ID
107412
Resolver ID
CaltechAUTHORS:20210112-080355149

Related works

Describes
https://arxiv.org/abs/1912.06955 (URL)

Funding

Department of Defense
Office of Naval Research (ONR)
N00014-16-1-2825
Office of Naval Research (ONR)
N00014-18-1-2877
NSF
PHY-1506284
NSF
PHY-1125846
Air Force Office of Scientific Research (AFOSR)
FA9550-17-1-0002
Army Research Office (ARO)
W911NF1520067
Gordon and Betty Moore Foundation
GBMF4543
Office of Naval Research (ONR)
N00014-15-1-2761
Samsung Electronics
NSF
ECCS-1541959
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
Japan Science and Technology Agency
JPMJCR15F3
Fannie and John Hertz Foundation
Paul and Daisy Soros Fellowship

Dates

Created
2021-01-12
Created from EPrint's datestamp field
Updated
2021-03-30
Created from EPrint's last_modified field