Controllable Growth of Monocrystalline MoS₂/Polycrystalline ReS₂ Lateral Heterojunction for High Quantum Efficiency Photodetector

Abstract Photodetectors (PDs) based on 2D transition metal dichalcogenides (2D TMDCs) heterojunction have become a potential candidate for frontier technology applications such as visible light communication (VLC). However, the conventional 2D TMDCs heterojunction PDs are facing problems with excessive dark current and low photoelectric conversion efficiency, resulting in the performance of PDs not meeting application requirements. Herein, the controllable growth of monocrystalline MoS 2 /polycrystalline ReS 2 lateral heterojunction via a two‐step chemical vapor deposition (CVD) method has been proposed. According to the result of density functional theory (DFT) calculation and the characterization of multiple parallel experiments under different conditions, the controllable growth of lateral heterojunction, especially the competition mechanism between lateral epitaxy and vertical stacking is systematically analyzed from different perspectives. Based on the analysis above, a strategy for preparing monocrystalline MoS 2 /polycrystalline ReS 2 lateral heterojunction with a large‐scale epitaxy layer and a high‐quality lateral structure is provided. Finally, PDs based on the as‐grown lateral heterojunction with responsivity and external quantum efficiency (EQE) up to 2.65 A W −1 and 506% are successfully applied to the VLC demonstration. This work provides a potential approach for the design and fabrication of optoelectronic devices with the requirement of high responsivity and photoelectric conversion efficiency.