Energy-Level Alignment at Interfaces between Transition-Metal Dichalcogenide Monolayers and Metal Electrodes Studied with Kelvin Probe Force Microscopy

Pavel A Markeev; Emad Najafidehaghani; Ziyang Gan; Kai Sotthewes; Antony George; Andrey Turchanin; Michel P de Jong

doi:10.1021/acs.jpcc.1c01612

Energy-Level Alignment at Interfaces between Transition-Metal Dichalcogenide Monolayers and Metal Electrodes Studied with Kelvin Probe Force Microscopy

J Phys Chem C Nanomater Interfaces. 2021 Jun 24;125(24):13551-13559. doi: 10.1021/acs.jpcc.1c01612. Epub 2021 Jun 10.

Authors

Pavel A Markeev¹, Emad Najafidehaghani², Ziyang Gan², Kai Sotthewes¹, Antony George², Andrey Turchanin², Michel P de Jong¹

Affiliations

¹ MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
² Institute of Physical Chemistry, Abbe Center of Photonics, Friedrich Schiller University, 07743 Jena, Germany.

Abstract

We studied the energy-level alignment at interfaces between various transition-metal dichalcogenide (TMD) monolayers, MoS₂, MoSe₂, WS₂, and WSe₂, and metal electrodes with different work functions (WFs). TMDs were deposited on SiO₂/silicon wafers by chemical vapor deposition and transferred to Al and Au substrates, with significantly different WFs to identify the metal-semiconductor junction behavior: oxide-terminated Al (natural oxidation) and Au (UV-ozone oxidation) with a WF difference of 0.8 eV. Kelvin probe force microscopy was employed for this study, based on which electronic band diagrams for each case were determined. We observed the Fermi-level pinning for MoS₂, while WSe₂/metal junctions behaved according to the Schottky-Mott limit. WS₂ and MoSe₂ exhibited intermediate behavior.