Hybrid Resonance-Enhanced Visible-to-Infrared Broadband Detection in InAs/GaSb Type-II Superlattice Photodetectors via a Microhole Array

Abstract

Broadband photodetection covering both visible and infrared wavelengths holds significant potential for sensing and reconnaissance applications that require simultaneous multiband imaging. However, extending the spectral response of a single infrared photodetector into the visible regime while maintaining low-noise operation at elevated temperatures remains a substantial challenge. This work presents an antireflection coating–Fabry–Pérot–guided-mode resonance (ARC-FP-GMR) hybrid-enhanced photodetector based on a back-illuminated InAs/GaSb type-II superlattice pπMn structure. This design synergistically combines the wavelength-selective enhancement of FP resonance with the lateral light confinement of GMR through a funnel-shaped microhole array grating fabricated on the epitaxial etch-stop and buffer layers, integrated with a bottom metal reflector to form an optical cavity. An additional SiO2 top layer further suppresses reflection in the visible band. The resulting GMR device achieves an average quantum efficiency of 66% across a 0.6–4.7 μm spectral range at 160 K, with a dark current density of 6.6 × 10–4 A/cm2 and a peak specific detectivity exceeding 2 × 1011 cm·Hz1/2/W. In addition, the device maintains a broadband detectivity above 1 × 109 cm·Hz1/2/W even at 250 K. Device-level simulations indicate a noise-equivalent temperature difference below 2 mK for a 1000 K target detection at 220 K. This study establishes a viable technical route toward high-performance broadband infrared detection systems for next-generation focal plane arrays.