Atom‐Precision Synthesis of MoS 2 /WS 2 Lateral Heterostructures for Prolonged Excitonic Lifetime

Transition metal dichalcogenide (TMD) lateral heterostructures provide unique platforms to study nanoscale physics, but progress is limited by the difficulty of producing high‐quality interfaces, which require atomic‐precision growth rather than simple stacking. We report a controllable two‐step chemical vapor deposition (CVD) process for directed epitaxy growth of MoS 2 /WS 2 monolayer lateral heterostructures. Atom‐resolution scanning tunneling microscopy measurements demonstrate an atomically sharp, defect‐free MoS 2 /WS 2 interface formed along the sulfur zigzag edge of MoS 2 , indicating an atomic‐substitution‐nucleation growth mechanism. Domain sizes of both MoS 2 and WS 2 can be precisely tuned from several to hundreds of micrometers. The zig‐zag interface creates an intermediate energy level at the junction, prolonging photogenerated carrier recombination lifetimes, in agreement with theoretical band‐structure calculations. This work establishes a scalable synthesis route to high‐quality TMDs lateral heterostructures with an atomic‐scale shape interface and tunable domain sizes, accelerating the applications in electronic and optoelectronic devices.