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

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 have been devoted, addressing such crucial issues simultaneously under two-dimensional (2D) confinement is yet to be realized. Here we design an ingenious strategy to synthesize record-breaking 4-inch length Fe-doped transition-metal dichalcogenides (TMDCs) single crystals on industry-compatible c-plane sapphire without special miscut angle. 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-inch 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. This article is protected by copyright. All rights reserved.