Vertical MoSe₂-WSe₂p-n Heterojunctions Grown by One-Pot Chemical Vapor Deposition for Ultrafast Photodetection

Two-dimensional transition metal dichalcogenides (TMDCs) have been extensively studied in the last decade due to their atomic thin structure and unique optoelectronic properties. In particular, lateral and vertical van der Waals heterostructures by combining different transition metal dichalcogenides (TMDCs) have been studied to develop the potential applications of two-dimensional materials. However, the optical properties are challenging due to the limited quality of TMDCs based heterojunctions. In this work, vertical MoSe2/WSe2 p-n heterojunctions have been synthesized by one-pot chemical vapor deposition (CVD) method. The MoSe2 -WSe2 heterostructure exhibits rectification characteristics of a p-n junction with the rectification ratio of 100 at ±10V bias. The phototransistor based on MoSe2/WSe2 p-n heterojunction shows a photoresponse of visible(638nm). The responsivity can reach up to 20 A/W, and the detectivity is 4.5\× 1013 Jones. Most importantly, the optical response time of the MoSe2/WSe2 p-n heterojunction is as fast as 28 ∼\μ s. The results indicate that vertical MoSe2/WSe2 p-n heterojunction could be a prospective candidate for high-performance optoelectronic devices.