Highly Responsive Near-Infrared Si/Sb₂Se₃ Photodetector via Surface Engineering of Silicon

The development of imaging technology and optical communication demands a photodetector with high responsiveness. As demonstrated by microfabrication and nanofabrication technology advancements, recent progress in plasmonic sensor technologies can address this need. However, these photodetectors have low optical absorption and ineffective charge carrier transport efficiency. Sb₂Se₃ is light-sensitive material with a high absorption coefficient, making it suitable for photodetector applications. We developed an efficient, scalable, low-cost near-infrared (NIR) photodetector based on a nanostructured Sb₂Se₃ film deposited on p-type micropyramidal Si (made via the wet chemical etching process), working on photoconductive phenomena. Our results proved that, at the optimized thickness of the Sb₂Se₃ layer, the proposed Si micropyramidal substrate enhanced the responsivity nearly two times, compared with that of the Sb₂Se₃ deposited on a flat Si reference sample and a glass/Sb₂Se₃ sample at 1064 nm (power density = 15 mW/cm²). More interestingly, the micropyramidal silicon-based device worked at 0 V bias, paving a path for self-bias devices. The highest specific detectivity of 2.25 × 10¹⁵ Jones was achieved at 15 mW/cm² power density at a bias voltage of 0.5 V. It is demonstrated that the enhanced responsivity was closely linked with field enhancement due to the Kretschmann configuration of Si pyramids, which acts as hot spots for Si/Sb₂Se₃ junction. A high responsivity of 47.8 A W^-1 proved it suitable for scalable and cost-effective plasmonic-based NIR photodetectors.