p -type Ohmic contact engineering in TMDs via MoO3-induced interface dipoles

Two-dimensional transition-metal dichalcogenide (TMD) electronics are often limited by high contact resistance arising from Fermi-level pinning and van der Waals tunneling barriers. Conventional bulk-doping approaches are generally incompatible with atomically thin materials because they can cause severe lattice damage, whereas interfacial charge-transfer doping offers a nondestructive alternative. Here, we investigate a monolayer MoO3 interlayer inserted between metal electrodes and TMD channels to realize p-type Ohmic contacts. First-principles calculations show that the high electron affinity of MoO3 drives electron transfer from the TMD and generates interfacial dipoles that shift the TMD Fermi level toward the valence-band edge. The MoO3 interlayer also spatially separates the metal from the TMD, thereby reducing gap states associated with direct metal–TMD hybridization. The contact properties of metal–MoO3–TMD heterostructures depend strongly on the MoO3–TMD band alignment: type-II MoO3–MoS2 interfaces exhibit reduced but generally finite hole Schottky barriers, whereas type-III MoO3–WSe2 interfaces produce favorable p-type Ohmic contacts. Density-functional-theory-based nonequilibrium Green's function simulations further predict enhanced on-state currents in MoO3-intercalated devices under idealized ballistic conditions. These results identify band-alignment-controlled interfacial dipoles as the dominant mechanism by which atomically thin MoO3 improves p-type TMD contacts for two-dimensional complementary electronics.