Design of Phosphorus-Containing MWIR Type-II Superlattices for Infrared Photon Detectors
AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
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Type-II strained layer superlattices SLSs offer a broad range of design degrees of freedom to help optimize their properties as absorber layers of infrared photon detectors. We theoretically examine a new class of mid-wavelength infrared 2-5 micron bandpass Type-II structures with two-layer InGaSbInPSb and four-layer InAsGaSbInAsInPSb SLS periods. Phosphorous-containing SLSs are a promising approach to improving infrared photon detector performance due to providing a new set of material properties, including favorable valence band offsets. P-based SLSs of four-layer type InAsGaSbInAsInPSb were found to be among the best 5-micron gap SLSs that we have modeled. Among the studied designs, the lowest dark current in an ideal structure is predicted for a four-layer 23.6 Angstrom InAs20 Angstrom GaSb23.6 Angstrom InAs60 Angstrom InP0.62Sb0.38 SLS. Its predicted ideal dark current is about 35 times lower than an n-type HgCdTe-based photodiode absorber and six times lower than a p-type HgCdTe one for the same bandgap, temperature, and dopant concentration. We also discuss a defect mitigation strategy that involves positioning the SLS gap in an energy range that avoids defect levels and show how this applies to the aforementioned P-containing SLS.
- Infrared Detection and Detectors
- Solid State Physics