Structure of the moiré exciton captured by imaging its electron and hole

Ouri Karni; Elyse Barré; Vivek Pareek; Johnathan D Georgaras; Michael K L Man; Chakradhar Sahoo; David R Bacon; Xing Zhu; Henrique B Ribeiro; Aidan L O'Beirne; Jenny Hu; Abdullah Al-Mahboob; Mohamed M M Abdelrasoul; Nicholas S Chan; Arka Karmakar; Andrew J Winchester; Bumho Kim; Kenji Watanabe; Takashi Taniguchi; Katayun Barmak; Julien Madéo; Felipe H da Jornada; Tony F Heinz; Keshav M Dani

doi:10.1038/s41586-021-04360-y

Structure of the moiré exciton captured by imaging its electron and hole

Nature. 2022 Mar;603(7900):247-252. doi: 10.1038/s41586-021-04360-y. Epub 2022 Mar 9.

Authors

Ouri Karni^#^{1

2}, Elyse Barré^#^{2

3}, Vivek Pareek^#⁴, Johnathan D Georgaras^#⁵, Michael K L Man^#⁴, Chakradhar Sahoo^#^{4

6}, David R Bacon⁴, Xing Zhu⁴, Henrique B Ribeiro², Aidan L O'Beirne^{2

7}, Jenny Hu¹, Abdullah Al-Mahboob⁴, Mohamed M M Abdelrasoul⁴, Nicholas S Chan⁴, Arka Karmakar⁴, Andrew J Winchester⁴, Bumho Kim⁸, Kenji Watanabe⁹, Takashi Taniguchi¹⁰, Katayun Barmak¹¹, Julien Madéo⁴, Felipe H da Jornada⁵, Tony F Heinz^{1

2}, Keshav M Dani¹²

Affiliations

¹ Department of Applied Physics, Stanford University, Stanford, CA, USA.
² SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
³ Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
⁴ Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan.
⁵ Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
⁶ Tata Institute of Fundamental Research, Hyderabad, Gopanpally, Serlingampalli, Telangana, India.
⁷ Department of Physics, Stanford University, Stanford, CA, USA.
⁸ Department of Mechanical Engineering, Columbia University, New York, NY, USA.
⁹ Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan.
¹⁰ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan.
¹¹ Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA.
¹² Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan. kmdani@oist.jp.

^# Contributed equally.

PMID: 35264760
DOI: 10.1038/s41586-021-04360-y

Abstract

Interlayer excitons (ILXs) - electron-hole pairs bound across two atomically thin layered semiconductors - have emerged as attractive platforms to study exciton condensation^1-4, single-photon emission and other quantum information applications^5-7. Yet, despite extensive optical spectroscopic investigations^8-12, critical information about their size, valley configuration and the influence of the moiré potential remains unknown. Here, in a WSe₂/MoS₂ heterostructure, we captured images of the time-resolved and momentum-resolved distribution of both of the particles that bind to form the ILX: the electron and the hole. We thereby obtain a direct measurement of both the ILX diameter of around 5.2 nm, comparable with the moiré-unit-cell length of 6.1 nm, and the localization of its centre of mass. Surprisingly, this large ILX is found pinned to a region of only 1.8 nm diameter within the moiré cell, smaller than the size of the exciton itself. This high degree of localization of the ILX is backed by Bethe-Salpeter equation calculations and demonstrates that the ILX can be localized within small moiré unit cells. Unlike large moiré cells, these are uniform over large regions, allowing the formation of extended arrays of localized excitations for quantum technology.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.