High-performance nanostructured uncooled MWIR PbSe photodetectors enabled by low-damage O+ ion implantation

Abstract

Uncooled mid-wave infrared (MWIR) photodetectors are an important development direction for next-generation infrared technology. However, due to the narrow bandgap and thermal noise, MWIR photo-detection is difficult to achieve with conventional photoconductive (PC) and photovoltaic (PV) photodetectors. This paper proposes a low-damage design based on O+ ion implantation in PbSe, achieving enhanced MWIR photoconductive response. The surface morphology of the nanostructures was observed. The optical bandgap of the thin films became smaller, making them more suitable for mid-infrared radiation detection. Increasing the implantation dose reduced the Urbach energy from 136.9 to 53.37 meV, indicating a reduction in band tail disorder and shallow defect states. An optimal dose (1 × 1018 cm−2) achieved a peak responsivity of 2.1 A/W at a wavelength of 4 μm, with a detectivity of 2.3 × 109 Jones at 4 μm, 300 K under bias voltage of 15 V, and chopping frequency of 400 Hz. The photoresponse is attributed to the formation of a built-in carrier separation region and the generation of deep-level traps, thereby enhancing carrier separation and prolonging minority carrier lifetime. Additionally, extremely high carrier mobility (4480–8320 cm2 V−1 s−1) was achieved, which improves the collection efficiency of photogenerated carriers. This work demonstrates a defect engineering strategy through O+ implantation, achieving excellent carrier mobility and responsivity for the high-performance uncooled MWIR photodetector.