Quantum-Confined States and Band Shifts Arising from Moiré Patterns in MoS<sub>2</sub>-WSe<sub>2</sub> Heterojunctions

ORAL

Abstract

Using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), the electronic states of heterojunctions formed by a monolayer of MoS2 on WSe2, grown on epitaxial graphene, have been investigated. A 4% lattice mismatch between the MoS2 and the WSe2 results in a moiré pattern with period 8.5 nm and corrugation height 0.1 nm. The band gap was found to form between the valence band (VB) of the WSe2 and the conduction band (CB) of the MoS2. Band edge shifts of 0.1-0.2 eV are observed depending on the location within the moiré unit cell. Furthermore, quantum-confined states at both the VB and CB edges were found to form near the minimum of the corrugation. Hybridization of orbitals was found to explain these features for the VB of the WSe2, however, intrinsic charge transfer between layers must also be considered for the features in the CB of the MoS2. We find that this electrostatic model results in band edge shifts and confined states that are consistent with the experiments.

*This work was supported in part by the Center for Low Energy Systems Technology (LEAST), one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

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Presenters

  • Dacen Waters

    • Physics, Carnegie Mellon Univ

Authors

  • Dacen Waters

    • Physics, Carnegie Mellon Univ

  • Yi Pan

    • Paul-Drude-Institut für Festkörperelektronik

  • Stefan Fölsch

    • Paul-Drude-Institut für Festkörperelektronik

  • Yifan Nie

    • Materials Science and Engineering, University of Texas at Dallas

  • Yu-Chuan Lin

    • Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, Pennsylvania State University

  • Bhakti Jariwala

    • Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, Pennsylvania State University

  • Kehao Zhang

    • Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, Pennsylvania State University

  • Kyeongjae Cho

    • Materials science and engineering, University of Texas at Dallas
    • Materials Science and Engineering, University of Texas at Dallas

  • Joshua Robinson

    • Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, Pennsylvania State University

  • Randall Feenstra

    • Physics, Carnegie Mellon Univ