University of Oulu

van Efferen, C., Murray, C., Fischer, J., Busse, C., Komsa, H.-P., Michely, T., & Jolie, W. (2022). Metal-insulator transition in monolayer MoS 2 via contactless chemical doping. 2D Materials, 9(2), 025026.

Metal-insulator transition in monolayer MoS2 via contactless chemical doping

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Author: van Efferen, Camiel1; Murray, Clifford1; Fischer, Jeison1;
Organizations: 1II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, Köln, 50937, Germany
2Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
3Faculty of Information Technology and Electrical Engineering, University of Oulu, Pentti Kaiteran Katu 1, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.7 MB)
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Language: English
Published: IOP Publishing, 2022
Publish Date: 2022-11-16


Much effort has been made to modify the properties of transition metal dichalcogenide layers via their environment as a route to new functionalization. However, it remains a challenge to induce large electronic changes without chemically altering the layer or compromising its two-dimensionality. Here, a non-invasive technique is used to shift the chemical potential of monolayer MoS2 through p- and n-type doping of graphene (Gr), which remains a well-decoupled 2D substrate. With the intercalation of oxygen (O) under Gr, a nearly rigid Fermi level shift of 0.45 eV in MoS2 is demonstrated, whereas the intercalation of europium (Eu) induces a metal–insulator transition in MoS2, accompanied by a giant band gap reduction of 0.67 eV. Additionally, the effect of the substrate charge on 1D states within MoS2 mirror-twin boundaries (MTBs) is explored. It is found that the 1D nature of the MTB states is not compromised, even when MoS2 is made metallic. Furthermore, with the periodicity of the 1D states dependent on substrate-induced charging and depletion, the boundaries serve as chemical potential sensors functional up to room temperature.

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Series: 2D materials
ISSN: 2053-1583
ISSN-E: 2053-1583
ISSN-L: 2053-1583
Volume: 9
Issue: 2
Article number: 025026
DOI: 10.1088/2053-1583/ac5d0f
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project Number 277146847—CRC 1238 (Subprojects A01 and B06). Support from the German Academic Exchange Service DAAD and the Academy of Finland via PPP Finland MODEST, Project IDs 57458732 (DAAD) and 321914 (Academy of Finland) is gratefully acknowledged. The authors thank CSC IT Center for Science for the generous grants of computer time.
Copyright information: © 2022 The Author(s). Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.