Enhanced optical response of a type-II superlattice mid-wave infrared detector enabled by ring-shaped metasurface structures

Abstract

To overcome photon-capture bottlenecks and low external quantum efficiency in type-II superlattice (T2SL) infrared detectors, we propose and experimentally realize a metal–semiconductor–metal (MSM) coupled architecture integrated with a metallic ring metasurface. The metasurface drives strong near-field localization and efficient in-coupling into the T2SL active region. Devices were fabricated on molecular-beam-epitaxy grown T2SL epitaxial wafers using electron-beam lithography and electron-beam evaporation. Measurements show that the annular MSM–T2SL structure markedly enhances photon capture and quantum efficiency (QE) across the mid-wave infrared (3–5 μm) band, the average QE increased from 18.3% to 26.2%, and the peak specific detectivity reached a maximum of 1.53 × 1012 cm Hz1/2/W.