Design considerations for a long-wavelength InAsSb detector diode

InAsSb can absorb light across the entire long wavelength range (8-12 mu m) and shares many of the other relevant basic materials properties of HgCdTe, the current incumbent detector technology for this band. We discuss here the device architectures in relation to the crystal growth technical aspects using molecular beam epitaxy and propose a simplified design consisting of an InAsSb absorber with a graded wider bandgap top layer of lattice matched AlInAsSb that exhibits a spontaneously formed p-n-junction. The 77 K device performance is predicted with a numerical model that indicates that quantum efficiencies of at least 75% should be achievable.