Enabling Reliable <i>p</i> -Type Transport in WSe2 Transistors from Monolayer to Multilayer

Abstract Transferring and contacting two-dimensional semiconductors often introduce Fermi-level pinning and high contact resistance, limiting efficient p-type transport in WSe2 transistors, particularly across varying thicknesses. Existing charge-transfer doping strategies have largely targeted channel modulation, with limited impact on contact resistance. Here, we report a contact engineering strategy based on ultrathin buffer layers that mitigate pinning through interfacial decoupling and induce local charge-transfer doping at the metal–semiconductor interface. Using self-limited O2 plasma oxidation for few-layer and bilayer WSe2, and evaporated interlayers for monolayers, we achieve consistent modulation of contact properties from few-layer to monolayer devices. This approach enhances hole conduction while suppressing electron injection, resulting in strongly improved p-type behavior and reduced contact resistance. Electrical measurements reveal substantial improvements in on-state current and contact performance across all thicknesses. These results establish a scalable pathway for achieving low-resistance p-type contacts in WSe2 and advance the development of complementary two-dimensional electronics.