Energy-Level Alignment at Interfaces between Transition-Metal Dichalcogenide Monolayers and Metal Electrodes Studied with Kelvin Probe Force Microscopy.
Pavel A MarkeevEmad NajafidehaghaniZiyang GanKai SotthewesAntony GeorgeAndrey TurchaninMichel P de JongPublished in: The journal of physical chemistry. C, Nanomaterials and interfaces (2021)
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.
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