Design and optimization of mid-infrared hot electron detector based on Al/GaAs fishnet nanostructure for CO2 sensing

Abstract

Hot electron detectors (HEDs) based on plasmon resonance can circumvent a semiconductor’s bandgap limitation and have high sensitivity, suitable for infrared gas detectors. Unfortunately, there are few literature reports on research in the mid-infrared (MIR) region. Herein, we design and optimize a HED based on Al/GaAs fishnet nanostructure for MIR C O 2 sensing, and its optical–electrical properties are numerically studied. Surface plasmons not only achieve strong absorptance at C O 2 emission wavelength but also greatly improve the photoelectric responsivity over a plane structure detector ( ∼ 42 t i m e s ). By changing the thickness of the GaAs layer, the detection wavelength can also be actively adjusted, achieving a larger range of multi-gas detection. The effect of external voltage is also considered. This work highlights a potential engineering application value and offers a path toward more compact and efficient MIR gas detectors.