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

[Image: see text] We studied the energy-level alignment at interfaces between various transition-metal dichalcogenide (TMD) monolayers, MoS(2), MoSe(2), WS(2), and WSe(2), and metal electrodes with different work functions (WFs). TMDs were deposited on SiO(2)/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 MoS(2), while WSe(2)/metal junctions behaved according to the Schottky–Mott limit. WS(2) and MoSe(2) exhibited intermediate behavior.