Bridging Synthesis and Controllable Doping of Monolayer 4 in. Length Transition‐Metal Dichalcogenides Single Crystals with High Electron Mobility

Abstract Epitaxial growth and controllable doping of wafer‐scale atomically thin semiconductor single crystals are two central tasks to tackle the scaling challenge of transistors. Despite considerable efforts are devoted, addressing such crucial issues simultaneously under 2D confinement is yet to be realized. Here, an ingenious strategy to synthesize record‐breaking 4 in. length Fe‐doped transition‐metal dichalcogenides (TMDCs) single crystals on industry‐compatible c ‐plane sapphire without special miscut angle is designed. Atomically thin transistors with high electron mobility (≈146 cm 2 V −1 s −1 ) and remarkable on/off current ratio (≈10 9 ) are fabricated based on 4 in. length Fe‐MoS 2 single crystals, due to the ultralow contact resistance (≈489 Ω µm). In‐depth characterizations and theoretical calculations reveal that the introduction of Fe significantly decreases the formation energy of parallel steps on sapphire surfaces and contributes to the edge‐nucleation of unidirectional alignment TMDCs domains (>99%). This work represents a substantial leap in terms of bridging synthesis and doping of wafer‐scale 2D semiconductor single crystals, which should promote the further device downscaling and extension of Moore's law.