Origin of strain-tuned Schottky barriers in TMD/metal interfaces: Dominant role of band-edge evolution

Abstract

Mechanical strain provides a powerful and experimentally accessible route for controlling Schottky barriers at interfaces between two-dimensional semiconductors such as transition metal dichalcogenides (TMDs) and metal electrodes. Despite growing experimental interest, the microscopic origin of strain-induced Schottky barrier height (SBH) modulation remains poorly understood. Here, we employ first-principles electronic structure calculations to investigate ten representative TMD/ metal interfaces, consisting of monolayer MoS2 and WSe2 contacted with Ag, Cu, Au, Pd and Pt under uniaxial strains ranging from-2% to +2%. It is demonstrated that tensile strain preferentially lowers the n-type SBH, yielding a nearly ohmic contact of 0.03 eV for MoS2/Ag interface, whereas compressive strain is more effective in reducing the p-type barriers. By decomposing the SBH into its physical contributions, we show that strain-induced shifts of the intrinsic TMD band edges constitute the dominant mechanism governing SBH modulation, while concurrent changes in the metal work function and interfacial dipole are comparable in magnitude but largely cancel each other. Furthermore, analysis of strain-induced band-edge evolution and charge redistribution reveals that valley-dependent electronic structure responses give rise to nonmonotonic SBH behavior in selected interfaces. These results provide a unified microscopic framework for understanding strain-tuned Schottky barriers and provide general design principles for contact engineering in two-dimensional electronic and optoelectronic systems.