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

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 cm2 V-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.