Comprehensive comparison regarding carrier separation characteristics of MoS2/WS2 lateral and vertical heterojunctions

Two-dimensional heterojunctions with a type-II band alignment have great potential for high-performance optoelectronic devices due to their inherent carrier separation properties. Herein, we synthesized lateral and vertical MoS 2 /WS 2 heterojunctions through a two-step chemical vapor deposition method and deeply investigated the impact of the interface structures on carrier separation efficiency. The experimental results demonstrate that the structures of MoS 2 /WS 2 heterojunctions can be controlled by adjusting the Mo/S ratio. In addition, lateral heterojunctions exhibit a significantly higher carrier separation efficiency than vertical heterojunctions. Specifically, the interlayer charge transfer time in the lateral heterojunction is approximately 1.2 ps, in contrast to the value of about 4.0 ps in the vertical heterojunction. First-principles simulation reveals that the lateral heterojunction has stronger interface coupling and orbital hybridization, contributing to its faster charge transfer rate. This work demonstrates the superiority of lateral heterojunctions in carrier separation, offering valuable insights for high-performance optoelectronic devices.