Metal-insulator transition in monolayer MoS<sub>2</sub> via contactless chemical doping
Camiel van Efferen, Clifford Murray, J. Fischer, Carsten Busse, Hannu‐Pekka Komsa, Thomas Michely, Wouter Jolie
Abstract
Abstract 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 MoS 2 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 MoS 2 is demonstrated, whereas the intercalation of europium (Eu) induces a metal–insulator transition in MoS 2 , accompanied by a giant band gap reduction of 0.67 eV. Additionally, the effect of the substrate charge on 1D states within MoS 2 mirror-twin boundaries (MTBs) is explored. It is found that the 1D nature of the MTB states is not compromised, even when MoS 2 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.