Rhenium Diselenide (ReSe(2)) Near‐Infrared Photodetector: Performance Enhancement by Selective p‐Doping Technique

In this study, a near‐infrared photodetector featuring a high photoresponsivity and a short photoresponse time is demonstrated, which is fabricated on rhenium diselenide (ReSe(2)) with a relatively narrow bandgap (0.9–1.0 eV) compared to conventional transition‐metal dichalcogenides (TMDs). The excellent photo and temporal responses, which generally show a trade‐off relation, are achieved simultaneously by applying a p‐doping technique based on hydrochloric acid (HCl) to a selected ReSe(2) region. Because the p‐doping of ReSe(2) originates from the charge transfer from un‐ionized Cl molecules in the HCl to the ReSe(2) surface, by adjusting the concentration of the HCl solution from 0.1 to 10 m, the doping concentration of the ReSe(2) is controlled between 3.64 × 10(10) and 3.61 × 10(11) cm(−2). Especially, the application of the selective HCl doping technique to the ReSe(2) photodetector increases the photoresponsivity from 79.99 to 1.93 × 10(3) A W(−1), and it also enhances the rise and decay times from 10.5 to 1.4 ms and from 291 to 3.1 ms, respectively, compared with the undoped ReSe(2) device. The proposed selective p‐doping technique and its fundamental analysis will provide a scientific foundation for implementing high‐performance TMD‐based electronic and optoelectronic devices.