Charge transfer tunneling contacts for n-type monolayer semiconductor toward high performance electronics

The emergence of two-dimensional (2D) semiconductors, particularly transition metal dichalcogenides (TMDs), shows great potential in revolution of the development of electronics. However, challenges in contact engineering, such as Fermi-level pinning and metal-induced gap states (MIGS) and disorders greatly hinder the high-performance devices based on 2D materials. Here, we propose a novel strategy to establish quasi-one-dimensional tunneling contacts through locally modulating the electronic properties of monolayer MoS₂ beneath the metal electrode by high-electron-affinity transition metal oxides (TMOs). MoO₃ is introduced to induce strong charge-transfer anti-doping in the contact region, effectively depleting free carriers and rendering the underlying MoS₂ electrically insulating and behaving as the tunneling layer. The Au/MoO₃-contacted monolayer-MoS₂ field-effect transistors exhibit near-ideal ohmic characteristics with an exceptionally low Schottky barrier height (SBH) of 1.6 meV, nearing the theoretical limit. The field effect mobility reaches 559.5 cm²/V∙s at 10 K. Moreover, we demonstrate that substitution of MoO₃ with V₂O₅ provides a means to tune the SBH, underscoring the versatility of this device fabrication strategy. This study presents a promising pathway for achieving efficient tunneling contacts in 2D electronics, paving the way for the advancement of next-generation high-performance devices.