Lateral Bilayer MoS 2 –WS 2 Heterostructure Photodetectors with High Responsivity and Detectivity

2D heterostructures combining different layered semiconductors have received great interest due to their intriguing electrical and optical properties. However, the arbitrary growth of layers in a lateral heterostructure remains a challenge. Here, the synthesis of large‐scale lateral bilayer (LBL) WS 2 –MoS 2 heterostructures is reported by a two‐step chemical vapor deposition route. Raman, photoluminescence, and second‐harmonic generation images show the sharp boundaries between WS 2 and MoS 2 domains in the heterostructure. Atomically resolved scanning transmission electron microscopy further reveals that sharp boundaries are formed by seamless connections via a lateral zigzag epitaxy between WS 2 and MoS 2 . Notably, the photodetector device based on the LBL WS 2 –MoS 2 heterostructure exhibits ultrahigh photoresponsivity and detectivity (6.72 × 10 3 A W −1 and 3.09 × 10 13 Jones for 457 nm laser light, respectively), orders of magnitude higher than those of MoS 2 and WS 2 monocrystals. These excellent performances render LBL WS 2 –MoS 2 heterostructures as promising candidates for next‐generation optoelectronics.