<scp> PtTe ₂ </scp> interface engineering for enhanced near‐infrared photoresponse in black silicon photodetectors

Abstract Highly responsive near‐infrared (NIR) photodetectors (PDs) are increasingly required for advanced photoelectric systems. While silicon‐based detectors benefit from mature fabrication and CMOS compatibility, their performance is limited by the intrinsic bandgap of 1.12 eV, which leads to weak responsivity in the NIR band. Herein, a high‐responsivity silicon‐based NIR PD is proposed by incorporating a heterostructure of black silicon (B‐Si) and PtTe 2 . The B‐Si integrated in the photosensitive region of a Si p‐i‐n diode introduces sub‐bandgap defect states, significantly enhancing NIR absorption. Further, the PtTe 2 film coated onto the B‐Si surface induces energy band bending and enhances the interfacial electric field, which together promote the separation and collection of photogenerated carriers. Additionally, the PtTe 2 film forms a passivation layer on the B‐Si surface, which repairs surface defects and suppresses carrier recombination, thereby reducing the dark current of the device. The PtTe 2 /B‐Si PD demonstrates remarkable NIR detection performance, achieving a responsivity of 0.64 A W –1 at 1064 nm and showing a 146% improvement over conventional silicon photodiodes, while maintaining excellent detectivity ( D *) of 3.54 × 10 11 Jones. This performance underscores the device's capability for weak‐light detection and positions it as a viable candidate for CMOS‐integrated NIR photonics. image