Nature of long-lived moiré interlayer excitons in electrically tunable MoS\(_{2}\)/MoSe\(_{2}\) heterobilayers

• Published in: arXiv.org
• Main Authors: Alexeev, Evgeny M, Purser, Carola M, Gilardoni, Carmem M, Kerfoot, James, Chen, Hao, Cadore, Alisson R, Rosa, Bárbara L T, Feuer, Matthew S G, Evans Javary, Hays, Patrick, Watanabe, Kenji, Taniguchi, Takashi, Tongay, Seth Ariel, Kara, Dhiren M, Atatüre, Mete, Ferrari, Andrea C
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 04.06.2024
• Subjects: Brillouin zones; Current carriers; Data processing; Electric dipoles; Electric fields; Excitons; Interlayers; Photoluminescence; Polarization; Service life assessment; Superlattices; Transition metal compounds
• ISSN: 2331-8422

Interlayer excitons in transition-metal dichalcogenide heterobilayers combine high binding energy and valley-contrasting physics with long optical lifetime and strong dipolar character. Their permanent electric dipole enables electric-field control of emission energy, lifetime, and location. Device material and geometry impacts the nature of the interlayer excitons via their real- and momentum-space configurations. Here, we show that interlayer excitons in MoS\(_{2}\)/MoSe\(_{2}\) heterobilayers are formed by charge carriers residing at the Brillouin zone edges, with negligible interlayer hybridization. We find that the moiré superlattice leads to the reversal of the valley-dependent optical selection rules, yielding a positively valued g-factor and cross-polarized photoluminescence. Time-resolved photoluminescence measurements reveal that the interlayer exciton population retains the optically induced valley polarization throughout its microsecond-long lifetime. The combination of long optical lifetime and valley polarization retention makes MoS\(_{2}\)/MoSe\(_{2}\) heterobilayers a promising platform for studying fundamental bosonic interactions and developing excitonic circuits for optical information processing.