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Resonant Cavity–Enhanced Photodiodes for Spectroscopy of CH Bonds
Author(s) -
Bainbridge Andrew,
Craig Adam P.,
Al-Saymari Furat,
Krier Anthony,
Marshall Andrew R. J.
Publication year - 2021
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.202100056
Subject(s) - photodiode , optoelectronics , materials science , absorption (acoustics) , infrared , substrate (aquarium) , wavelength , resonance (particle physics) , absorption spectroscopy , spectroscopy , optics , atomic physics , physics , oceanography , composite material , geology , quantum mechanics
Resonant cavity‐enhanced photodiodes targeted within the spectral region of absorption by CH bonds are demonstrated. The 3.0 – 3.3 μ m region of the infrared spectrum contains many substances that are useful to measure spectroscopically. However, the measurement of individual substances requires a high spectral specificity, that is achieved by the resonant cavity photodiodes with spectral response widths of < 40 nm . Two material systems are investigated for detection at this wavelength range—an InAs absorber on an InAs substrate and an InAsSb absorber lattice‐matched to a GaSb substrate. The resonance wavelength of the InAs‐based device responds at ≈ 3.3 μ m , closely tuned to an absorption peak of methane to allow precise sensing of this gas. At 300 K a quantum efficiency of 52 % is achieved, with a specific detectivity of 2.5 × 10 10 cm Hz / W . The InAsSb‐based device is sensitive at ≈ 3.7 μ m , but the structure could be tuned to the methane absorption peak. Devices could be simply created to target other substances in the C−H absorption region by altering the layer thicknesses in the structure. Both structures can be used for spectrally specific gas sensing in this region of the infrared.