PtTe₂ 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 PtTe₂. 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 PtTe₂ 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 PtTe₂ 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 PtTe₂/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 × 10¹¹ Jones. This performance underscores the device's capability for weak-light detection and positions it as a viable candidate for CMOS-integrated NIR photonics.

Keywords

black silicon / interface engineering / near-infrared / photodetector / PtTe₂

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