In-Plane Mosaic Potential Growth of Large-Area 2D Layered Semiconductors MoS₂–MoSe₂ Lateral Heterostructures and Photodetector Application

Abstract

Considering the unique layered structure and novel optoelectronic properties of individual MoS₂ and MoSe₂, as well as the quantum coherence or donor-acceptor coupling effects between these two components, rational design and artificial growth of in-plane mosaic MoS₂/MoSe₂ lateral heterojunctions film on conventional amorphous SiO₂/Si substrate are in high demand. In this article, large-area, uniform, high-quality mosaic MoS₂/MoSe₂ lateral heterojunctions film was successfully grown on SiO₂/Si substrate for the first time by chemical vapor deposition (CVD) technique. MoSe₂ film was grown along MoS₂ triangle edges and occupied the blanks of the substrate, finally leading to the formation of mosaic MoS₂/MoSe₂ lateral heterojunctions film. The composition and microstructure of mosaic MoS₂/MoSe₂ lateral heterojunctions film were characterized by various analytic techniques. Photodetectors based on mosaic MoS₂/MoSe₂ lateral heterojunctions film, triangular MoS₂ monolayer, and multilayer MoSe₂ film are systematically investigated. The mosaic MoS₂/MoSe₂ lateral heterojunctions film photodetector exhibited optimal photoresponse performance, giving rise to responsivity, detectivity, and external quantum efficiency (EQE) up to 1.3 A W^-1, 2.6 × 10¹¹ Jones, and 263.1%, respectively, under the bias voltage of 5 V with 0.29 mW cm^-2 (610 nm), possibly due to the matched band alignment of MoS₂ and MoSe₂ and strong donor-acceptor delocalization effect between them. Taking into account the similar edge conditions of transition metal dichalcogenides (TMDCs), such a facile and reliable approach might open up a unique route for preparing other 2D mosaic lateral heterojunctions films in a manipulative manner. Furthermore, the mosaic lateral heterojunctions film like MoS₂/MoSe₂ in the present work will be a promising candidate for optoelectronic fields.