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O: Fachverband Oberflächenphysik

O 22: Poster Session - 2D Materials Beyond Graphene: Growth, Structure and Substrate Interaction

O 22.3: Poster

Montag, 16. März 2020, 18:15–20:00, P1A

Gating monolayer MoS2 by charging its substrate — •Camiel van Efferen, Clifford Murray, Jeison Fisher, Joshua Hall, and Thomas Michely — II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

We gate quasi-freestanding monolayer MoS2, grown by molecular beam epitaxy (MBE) on graphene (Gr) on Ir(111) [1], by introducing intercalants between Gr and Ir(111). Using intercalants like Eu and O, we control the position of the Gr Dirac point, allowing us to n- or p-gate the Gr and in turn also the MoS2. Applying a combination of scanning tunneling microscopy and spectroscopy we measure the effects of the gating on the band structure of monolayer MoS2, which has previously been studied using comprehensive scanning tunneling spectroscopy [2]. In ungated MoS2/Gr/Ir(111) a 1D hole gas is found around the 4|4E mirror twin boundaries of MBE-grown MoS2, a consequence of band bending around the charged boundary. We investigate how the band bending and the 1D hole gas are affected by the gating, due to changes in the screening environment and the charge transfer from the substrate. Moreover, as a consequence of gating, we observe also a shift in the periodicity of the confined states in the mirror twin boundaries.

[1] Joshua Hall et al., 2D Materials 5, 025005 (2018)

[2] Clifford Murray et al., Phys. Rev. B 99, 115434 (2019)