InGaAs/InAsSb ternary SLS MWIR photodetectors

The strained layer superlattice (SLS) class of materials is a growing area of research interest for the development of high-performance mid-wavelength infrared (MWIR) detectors. InAs/(In)GaSb is the first and most thoroughly studied SLS material system, but relatively short Shockley-Reed-Hall (SRH) carrier lifetime has prompted exploration of alternative material systems. Significant improvement in minority carrier lifetime has been demonstrated using InAs/InAsSb, but weak absorption coefficient and short diffusion length limit the detector quantum efficiency for this material system. To address these shortcomings, we explore InGaAs/InAsSb as a flexible material system for the design of MWIR photodetectors. Utilizing two ternary materials as the superlattice constituents enables independent tuning of material parameters such as absorption coefficient and carrier effective mass for a given cutoff wavelength. We present conceptual designs as well as experimental results for InGaAs/InAsSb MWIR photodetectors that demonstrate performance improvements made possible by the flexibility of this ternary design scheme.