Wafer-Scale Synthesis of V₂O₅ Single Crystals for Ultrahigh Doping of 2D Materials

The controllable growth of wafer-scale single-crystalline 2D materials is foundational for future electronic and photonic applications. Layer-by-layer integration enables the fabrication of 2D heterostructure with multiple functionalities, such as doping of 2D materials, which enhances the conductivity and tunes work function to improve electrical contacts. The synthesis of wafer-scale single-crystalline 2D dopants enables subsequent integration with other 2D materials, which can avoid lattice defects and interface scattering centers typically associated with heteroatom doping or amorphous dopant. However, the synthesis of single-crystalline 2D dopants remains unexplored. Here, this study reports an effective approach to synthesize centimetre-sized V₂O₅ bulk single-crystal and inch-sized V₂O₅ single-crystalline films, which can efficiently dope graphene and transition metal dichalcogenides (TMDs). Interfacing graphene with single-crystalline V₂O₅ enables hole doping of graphene, achieving a carrier density of ≈10¹³ cm^-2 and carrier mobility of ≈4400 cm² V^-1 s^-1. The preservation of carrier mobility of graphene is enabled by a defect-free interface and large energies of surface optical phonon modes of V₂O₅. Combined with reliable wafer-scale synthesis and layer-by-layer stacking techniques for fabricating 2D materials/V₂O₅ heterostructure, the results provide a scalable method for uniform, stable and efficient doping, facilitating the integration of 2D heterostructure into high-speed logic circuits and photonics for optical communications.