Modeling of very long infrared wavelength InAs/GaInSb strained layer superlattice detectors

The optimal performance of VLWIR (15 μm cutoff wavelength) photovoltaic detectors is assessed theoretically. The electronic band structures are computed with a fourteen-band restricted-basis envelope function Hamiltonian that includes terms copuling heavy and light holes at the superlattice interfaces. These terms describe the type of bonding at the interfaces (InSb or GaAs-like) and result in approximately 25 meV energy gap corrections in thin superlattices in comparison with conventional envelope-function approaches that neglect these terms. Auger lifetimes and upper bounds to detector detectivities are computed with these accurate band structures. The Auger transition rate calculations include Umklapp terms in the transition amplitude.