LWIR interband cascade photodetectors with InAs/InAsSb II type superlattice absorber

The properties of long-wave infrared (LWIR) interband cascade photodetectors (ICIPs) with type II superlattices (T2SLs) and gallium-free (Ga-free) InAs/InAsSb absorbers were determined using photoluminescence (PL) and spectral response (SR) measurements. The heterostructures were grown by molecular beam epitaxy (MBE) on a GaAs substrate. Three structures with different numbers of stages were compared. The structures were optimized for 10.7 μm at 300 K. Moreover, theoretical calculations were performed using APSYS to compare with the experimental results. The PL results provided information on transitions from minibands and intragap states in the studied structures. SR measurements helped isolate transitions involving minibands, which facilitated the analysis of visible transitions in the PL spectra, where point defect (NPD) transitions were also observed.