Design of resonant cavity-enhanced InAs/GaSb superlattice LWIR photodetector

Type-II superlattices have recently emerged as a focal point in long-wavelength infrared (LWIR) detection, showcasing remarkable potential across various applications. In this work, we have conducted a theoretical investigation into the band structure and optical properties of 14/7 monolayers (ML) InAs/GaSb superlattices (SLs), employing density functional theory. Our findings indicate that the energy gap of these SLs is determined to be 0.111 eV through energy band structure analysis using the Heyd-Scuseria-Ernzerhof method. Moreover, we have designed a resonant cavity-enhanced "Phi" structure for the 14/7 ML InAs/GaSb SLs infrared detector. This innovative design markedly enhances absorption efficiency, increasing it from 16.48% to an impressive 76.35% at the 11.2 mu m wavelength. Further analysis includes a detailed examination of the electric field distribution within this structure and a comprehensive examination of the enhanced plasmonic resonator's perfect absorption phenomenon. The results from these analyses underscore the exceptional absorption capabilities of our resonant cavity-enhanced infrared detector, indicating its potential for significant applications in LWIR SLs focal plane.