Paper

Moiré-localized interlayer exciton wavefunctions captured by imaging its electron and hole constituents

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

2021

Overview

Interlayer excitons (ILXs) - electron-hole pairs bound across two atomically thin layered semiconductors - have emerged as attractive platforms to study exciton condensation, single-photon emission and other quantum-information applications. Yet, despite extensive optical spectroscopic investigations, critical information about their size, valley configuration and the influence of the moiré potential remains unknown. Here, we captured images of the time- and momentum-resolved distribution of both the electron and the hole that bind to form the ILX in a WSe2/MoS2 heterostructure. We thereby obtain a direct measurement of the interlayer exciton diameter of ~5.4 nm, comparable to the moiré unit-cell length of 6.1 nm. Surprisingly, this large ILX is well localized within the moiré cell to a region of only 1.8 nm - smaller than the size of the exciton itself. This high degree of localization of the interlayer exciton 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, thus allowing the formation of extended arrays of localized excitations for quantum technology.

• Publisher: Cornell University Library, arXiv.org
• Subject: Bethe-Salpeter equation / Diameters / Electrons / Emission analysis / Excitons / Heterostructures / Holes (electron deficiencies) / Interlayers / Photon emission / Unit cell / Wave functions