Ultra-broadband single-junction photodetector based on InAs/GaSb superlattices

Effectively extracting photogenerated carriers from both high- and low-energy photons remains a critical challenge in the development of ultra-broadband photodetectors spanning the short- to long-wave spectrum. This work presents an ultra-broadband single-junction photodetector based on InAs/GaSb superlattices. The device incorporates two distinct absorption regions-short- and long-wavelengths-to synergistically enhance the spectral response. To optimize carrier transport and suppress dark current, an InAs/GaSb/AlSb/GaSb barrier structure is introduced, enabling broadband spectral detection from 0.4 to 14 μm. The novel, to the best of our knowledge, design addresses the spectral limitations of conventional single-junction photodetectors by synergistically optimizing both the short- and long-wavelength absorption modules. Energy band engineering across the material layers effectively reduces the energy loss of photogenerated carriers. The present photodetector achieves high quantum efficiency and low noise performance, with significant dark current suppression attributed to the engineered barrier structure. At 77 K under a saturation bias of -30 mV, the PI₁I₂MN-structured photodetector achieves a peak quantum efficiency of 34.48%, an average peak detectivity of 1 × 10¹¹ Jones, and a dark current density of 7.08 × 10^-4 A/cm²-outperforming the conventional NIPBPIMN structure by factors of 2.6, 3.3, and 0.5, respectively.