Homo-metal-element mediated surface modification of sapphire for robust epitaxy of wafer-scale single-crystalline 2D...

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) single-crystal wafers have been envisioned as promising channel materials to drive semiconductor technology down to the atomic limit. Although several efforts have been made, wafer-scale single crystal growth with high robustness and efficiency remains challenging. Here, we design a homo-metal-element (W/Mo and Al) surface modification strategy of commercial C/M sapphire inducing a low-symmetry modification layer. This design enables the robust epitaxial growth of 2-inch scale monolayer WS₂ or MoS₂ single-crystal wafers via a facile chemical vapor deposition (CVD) method. Since no exogenous elements are introduced on the substrate surface, the derived monolayer WS₂ single crystals present high crystal quality and no impurity introduction, as evidenced by multi-scale characterizations and field effect transistors array fabrications (on/off ratio >10⁸ and mobility ~48.2 cm²V^-1 s^-1). This work should hereby propel the wafer-scale synthesis and the internal epitaxial mechanism exploration of 2D TMDCs single crystals via substrate surface modulation, and promote the high-performance applications in various fields.