Quasi‐Covalent Conductive Bridges in 2D Semimetal‐Semiconductor Contacts

ABSTRACT

Achieving ultralow contact resistance in two‐dimensional transition metal dichalcogenide semiconductors remains a key bottleneck for further device scaling. Although all‐2D semimetal/semiconductor van der Waals (vdW) contacts effectively suppress metal‐induced gap states, mitigate interfacial defects, and alleviate Fermi‐level pinning, the intrinsic vdW gap inevitably introduces a substantial tunneling barrier that severely limits carrier injection. Here, based on first‐principles calculations and quantum transport simulations, we propose a quasi‐covalent conductive bridge (QCCB) contact strategy, in which atomic conductive bridges transform weak van der Waals interactions into quasi‐covalent bonding, thereby enhancing interlayer coupling and reconstructing the interfacial electronic structure. Using a 1T′‐MoSe ₂ /2H‐WSe ₂ heterostructure as a model system, we show that the introduction of atomic conductive bridges simultaneously realizes Ohmic contact and complete suppression of the tunneling barrier. The tunneling probability increases from ∼0.4% in conventional vdW contacts to nearly 100% at a bridge density of 7 atoms nm ⁻² , leading to a several‐hundred‐fold enhancement in charge transport efficiency and enabling a nearly barrier‐free transport channel. Consequently, the p‐type WSe ₂ QCCB contact with a bridge density of 7 atoms nm ⁻² achieves an ultralow contact resistance approaching the quantum limit (∼51 Ω·µm). This strategy provides a general route for developing next‐generation low‐power, high‐performance TMD‐based electronic devices.