Polarization‐Encoded Transmission Enabled by PtSe 2 /Si PIN Photodetectors with Circular Groove Light‐Trapping Architecture

Abstract 2D PtSe 2 shows promise for extending Si photodetection to the short‐wave infrared (SWIR) but faces integration challenges. A high‐performance PtSe 2 /I‐Si/N + ‐Si PIN photodetector on Si circular groove light‐trapping structures is demonstrated. Using in situ selenization and a Sn diffusion barrier, highly crystalline, uniform 1T‐PtSe 2 films are achieved on the grooved substrate. The grooves significantly enhance broadband light absorption (532–2200 nm) via grating diffraction and a strong built‐in electric field for efficient carrier separation. The device exhibits significant polarized light intensity‐sensitive photoresponse, with an extinction ratio of 137 at 532 nm (8 × higher than planar devices). At 2200 nm, responsivity (1.6 µA W −1 at −2 V) and detectivity (5 × 10 5 Jones) show 133 × and 100 × improvements over groove‐free structures, respectively, with a 33 kHz bandwidth. Successful polarization‐encoded transmission (“CODE” at 1310 nm, “MNNU” at 1550 nm) validates the strategy. The groove structure enhances photon harvesting through prolonged optical path and diffraction, while the SnO 2 barrier suppresses Pt‐Si intermixing, reducing interfacial defects. This establishes a scalable paradigm of topological light‐trapping engineering for broadband photodetectors in imaging and communication.