Ultralow Contact Resistance in Two-Dimensional Semiconductor Transistors Approaching the Quantum Limit

The miniaturization of silicon-based integrated circuits is approaching its limits owing to strong quantum confinement and interfacial effects. Atomically thin, two-dimensional (2D) materials show great potential to break such a limit, but the realization of an ultralow contact resistance (R_C) remains a key challenge because of natural van der Waals gaps in 2D semiconductors and weak interlayer coupling at the metal-semiconductor junction (MSJ) interface. Herein, we develop efficient strategies to tune R_C and the Schottky barrier height (SBH) by combining high-throughput first-principles calculations and machine-learning techniques. Notably, we reveal that hydrogen-bonding interactions at the MSJ interface containing -OH functional groups significantly enhance metal/2D semiconductor coupling, leading to effective tunneling-barrier reduction and charge redistribution. Such interactions enable the formation of Ohmic contacts, yielding ultralow values of R_C approaching the quantum limit. Through symbolic regression, we establish robust physical models by linking R_C with critical properties, including SBH and the tunneling-specific resistivity. These findings provide critical insights and efficient approaches for designing next-generation transistor architectures with superior electrical-contact performance.