In Situ Chemical Vapor Deposition‐Grown Trilayer ReSe ₂ /Silicon‐On‐Insulator (SOI) Heterostructure for High Performance Broadband Photodetection

Two‐dimensional Rhenium diselenide (ReSe 2 ), with its anisotropic optoelectronic properties, has gained significant interest for scientific explorations. Herein, we report a direct chemical vapor deposition (CVD) growth of 2D ReSe 2 on a silicon‐on‐insulator (SOI) substrate for the first time and demonstrate its application as a high‐performance broadband photodetector (PD). In situ CVD‐grown trilayer ReSe 2 /p‐SOI heterojunction with a clean interface leverages the strong light absorption of ReSe 2 and efficient carrier separation at the ReSe 2 /p‐SOI interface, resulting in a high light‐to‐dark current ratio of ∼10 4 . The heterojunction PD demonstrates a broadband photoresponse spanning the UV (365 nm) to near‐infrared (1000 nm) region, with peak sensitivity in the visible wavelength range. A high responsivity of up to ∼21 A W −1 , a peak detectivity of 4.6 × 10 10 Jones, and a large linear dynamic range of ∼71.9 dB are achieved under 532 nm laser excitation on the heterojunction PD. PL and band alignment analysis, along with density functional theory (DFT) calculations, reveal a type‐II n‐ReSe 2 /p‐SOI heterojunction with interfacial charge transfer from p‐Si to n‐ReSe 2 upon illumination, promoting efficient carrier separation. Fast photoresponse with a rise time of ∼10 µs further highlights the suitability of the device for high‐speed optoelectronic applications.