Resolidified Chalcogen-Assisted Growth of Bilayer Semiconductors with Controlled Stacking Orders

Bilayer semiconductors have attracted much attention due to their stacking-order-dependent properties. However, as both 3R- and 2H-stacking are energetically stable at high temperatures, most of the high-temperature grown bilayer materials have random 3R- or 2H-stacking orders, leading to non-uniformity in optical and electrical properties. Here, a chemical vapor deposition method is developed to grow bilayer semiconductors with controlled stacking order by modulating the resolidified chalcogen precursors supply kinetics. Taking tungsten disulfide (WS₂ ) as an example, pure 3R-stacking (100%) and 2H-stacking dominated (87.6%) bilayer WS₂ are grown by using this method and both show high structural and optical quality and good uniformity. Importantly, the bilayer 3R-stacking WS₂ shows higher field effect mobility than 2H-stacking samples, due to the difference in stacking order-dependent surface potentials. This method is universal for growing other bilayer semiconductors with controlled stacking orders including molybdenum disulfide and tungsten diselenide, paving the way to exploit stacking-order-dependent properties of these family of emerging bilayer materials.