A two-dimensional PtSe₂ thin film coupled with a graphene/Si Schottky junction for a high-performance photodetector

Silicon materials are irreplaceable in the modern information society because of their rich resource, low price, and mature manufacturing technology for optoelectronics. However, improving the responsivity and response speed of silicon-based photodetectors is still a challenge. Here, a double-heterojunction photodetector (PD) by coupling two-dimensional PtSe₂ thin film with a graphene/silicon Schottky junction is proposed. The introduction of PtSe₂ enhances the built-in electric field of the device, thus suppressing the dark-state current and promoting the separation of photogenerated electron-hole pairs. Under 808 nm laser illumination, the PtSe₂/graphene/Si PD exhibits an optimal responsivity, specific detectivity, and response speed of 0.81 A W^-1, 1.24 × 10⁹ Jones, and 43.6/51.2 μs, respectively. These performance indexes are obviously better than the corresponding graphene/Si device. Furthermore, the PtSe₂/graphene/Si PD has good environmental durability and photoresponse ability from the ultraviolet to near-infrared. This work will provide new possibilities for designing novel silicon-based photodetection devices with high performance and fast response.