Spectrally Selective Mid-Wave Infrared Detection Using Fabry-Pérot Cavity Enhanced Black Phosphorus 2D Photodiodes

Thin two-dimensional (2D) material absorbers have the potential to reduce volume dependent thermal noise in infrared detectors.However, any reduction in noise must be balanced against lower absorption from the thin layer, which necessitates advanced optical architectures.Such architectures can be particularly effective for applications that require detection only within a specific narrow wavelength range.This study presents a Fabry-Pérot cavity enhanced bP/MoS2 mid-wave infrared (MWIR) photodiode.This simple structure enables tunable narrow-band (down to 0.42 µm full-widthhalf-maximum) photodetection in the 2-4 µm range by adjusting the thickness of the Fabry-Pérot cavity resonator.This is achieved whilst maintaining room temperature performance metrics comparable to previously reported 2D MWIR detectors.Zero bias specific detectivity and responsivity values of 1.7 × 10 9 cm Hz 1/2 W -1 and 0.11 A W -1 at λ = 3.0 µm are measured, with rise/fall times around 7 µs.These results introduce a promising family of 2D detectors with applications in MWIR spectroscopy.