Hidden Vacancy Benefit in Monolayer 2D Semiconductors

Abstract Monolayer 2D semiconductors (e.g., MoS₂) are of considerable interest for atomically thin transistors but generally limited by insufficient carrier mobility or driving current. Minimizing the lattice defects in 2D semiconductors represents a common strategy to improve their electronic properties, but has met with limited success to date. Herein, a hidden benefit of the atomic vacancies in monolayer 2D semiconductors to push their performance limit is reported. By purposely tailoring the sulfur vacancies (SVs) to an optimum density of 4.7% in monolayer MoS₂, an unusual mobility enhancement is obtained and a record‐high carrier mobility (>115 cm² V⁻¹ s⁻¹) is achieved, realizing monolayer MoS₂ transistors with an exceptional current density (>0.60 mA µm⁻¹) and a record‐high on/off ratio >10¹⁰, and enabling a logic inverter with an ultrahigh voltage gain >100. The systematic transport studies reveal that the counterintuitive vacancy‐enhanced transport originates from a nearest‐neighbor hopping conduction model, in which an optimum SV density is essential for maximizing the charge hopping probability. Lastly, the vacancy benefit into other monolayer 2D semiconductors is further generalized; thus, a general strategy for tailoring the charge transport properties of monolayer materials is defined.