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Enhanced broadband quantum efficiency in LWIR T2SL detectors with guided-mode resonance structure
Optics Express
|January 29, 2025
Summary
Guided-mode resonance structures significantly boost quantum efficiency in Type-II superlattice detectors for long-wavelength infrared imaging. This innovation enhances light absorption in thin detectors, improving performance for critical applications.
Area of Science:
- Optoelectronics
- Infrared detection technology
- Materials science
Background:
- Type-II superlattice (T2SL) detectors are crucial for long-wavelength infrared (LWIR) applications (8-14 µm) in space, medical, and defense sectors.
- Improving quantum efficiency (QE) in T2SL detectors is challenged by the need for thicker absorbers, which increase dark current and manufacturing complexity.
- Short carrier lifetimes in T2SLs limit traditional light absorption enhancement methods like absorber thickening.
Purpose of the Study:
- To enhance the quantum efficiency (QE) of T2SL LWIR detectors.
- To maintain a thin active layer (AL) for efficient carrier collection.
- To overcome limitations of conventional methods for improving light absorption in T2SL detectors.
Main Methods:
- Introduction of a guided-mode resonance (GMR) structure into T2SL LWIR detectors.
- Fabrication of the GMR structure using a surface grating array and a sub-absorber gold (Au) mirror.
- Optimization of grating parameters (5 µm period, 0.6 fill factor) guided by finite-difference time-domain (FDTD) simulations.
Main Results:
- The GMR structure enhanced light trapping and introduced additional resonance modes.
- Optimized GMR design significantly increased light absorption, confirmed by simulations and experiments.
- GMR-enhanced T2SL detectors showed a 2.58x higher QE than conventional LWIR detectors.
- A 1.33x higher QE was observed compared to Fabry-Pérot (FP) resonance detectors in the 6-11 µm range.
- The GMR detector exhibited a broader cut-off wavelength (9.3 µm) and superior QE with similar dark current density.
Conclusions:
- Guided-mode resonance is an effective strategy for enhancing QE in thin T2SL LWIR detectors.
- GMR structures offer a pathway to improved performance in LWIR detection without compromising carrier collection efficiency.
- This approach advances LWIR detector technology for demanding applications requiring high sensitivity and specific wavelength ranges.
