Abstract
Quantum cascade detectors (QCDs) are mid-infrared and far-infrared, low-noise, photovoltaic detectors utilizing intersubband transitions. This Letter presents an InAs/AlAs0.16Sb0.84 based QCD lattice matched to an InAs substrate. This material system exhibits properties like a low effective electron mass of the well material of 0.023 m0, beneficial for higher optical absorption strength, and a high conduction band offset of 2.1 eV, allowing the design of QCDs in the mid-infrared and near-infrared region. The presented QCD has a peak spectral response at 2.7 μm (0.459 eV), the center of a CO2 absorption band. To enable top side illumination, a grating was implemented. This additionally bypasses absorption by the narrow bandgap 0.345 eV (3.54 μm) InAs substrate material. The QCD has a peak responsivity at a room temperature of 5.63 mA/W and a peak specific detectivity of 1.14 × 108 Jones.
Highlights
Quantum cascade detectors (QCDs) are fundamentally different than other classes of photodetectors like interband detectors, including type-II and other superlattice detectors, where optical transitions occur between the valence and conduction band.4 Interband detectors excel in the wavelength range between the visible and MIR and offer high responsivity as well as broad band absorption, typically exceeding 2 eV
This Letter presents an InAs/AlAs0.16Sb0.84 based QCD lattice matched to an InAs substrate
The advantage of QCDs lies in longer wavelength photodetection and applications where high-speed detection is required: Recently, a QCD with a 3-dB bandwidth of more than 20 GHz was reported,7 compared to the 3-dB bandwidth of up to 7.04 GHz for a type-II superlattice detector
Summary
This material system exhibits properties like a low effective electron mass of the well material of 0.023 m0, beneficial for higher optical absorption strength, and a high conduction band offset of 2.1 eV, allowing the design of QCDs in the mid-infrared and near-infrared region. QCDs are fundamentally different than other classes of photodetectors like interband detectors, including type-II and other superlattice detectors, where optical transitions occur between the valence and conduction band.4 Interband detectors excel in the wavelength range between the visible and MIR and offer high responsivity (above 100 mA/W5,6) as well as broad band absorption, typically exceeding 2 eV.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
