Chemical Vapor Deposition of 4 Inch Wafer‐Scale Monolayer MoSe2

2D semiconducting transition metal dichalcogenides (TMDs) are considered promising building blocks for emergent electronic and optoelectronic devices. As one of the representatives of 2D semiconductors, monolayer MoSe2 has excellent electrical and optical properties and has attracted a lot of research interest recently. To realize various device applications, large‐scale synthesis of monolayer MoSe2 with high crystal quality is critical, yet remains challenging. Herein, the growth of monolayer MoSe2 at a 4 inch wafer‐scale by chemical vapor deposition is demonstrated. Based on a multisource design and vertical placement of substrates, wafer‐scale continuity and uniformity of layer thickness, e.g., the monolayer, are achieved. This growth technique is also applicable to the wafer‐scale growth of other 2D semiconductors such as WS2 and MoS2.