Metal-insulator transition in monolayer MoS2via contactless chemical doping

• Main Authors: Busse, C. (Author), Fischer, J. (Author), Jolie, W. (Author), Komsa, H.-P (Author), Michely, T. (Author), Murray, C. (Author), Van Efferen, C. (Author)
• Format: Article
• Language: English
• Published: IOP Publishing Ltd 2022
• Subjects: Chemical doping; Chemical potential; Contact less; contactless doping; Contactless doping; Density functional theory; density-functional theory; Density-functional-theory; Energy gap; Graphene; graphene substrate; Graphene substrates; Layered semiconductors; Metal insulator boundaries; Metal insulator transition; metal-insulator transition; Molybdenum compounds; monolayer MoS2; Monolayer MoS2; Monolayers; Property; Scanning tunneling microscopy; scanning tunneling microscopy/spectroscopy; Scanning tunneling microscopy/spectroscopy; Semiconductor insulator boundaries; Substrates; Transition metal dichalcogenides (TMD); Transition metals; Twin boundaries
• Online Access: View Fulltext in Publisher

 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. © 2022 The Author(s). Published by IOP Publishing Ltd.