Optimization of the vertical hole mobility in LWIR type II superlattices through high-fidelity semiconductor modeling

Despite significant success in InAs/InAsSb mid-wave infrared (MWIR) type II superlattice (T2SL) infrared (IR) focal plane arrays (FPAs), long-wave infrared (LWIR) T2SL IR FPAs continue to suffer from low quantum efficiency (QE) due to low hole mobility. In response, DEVCOM ARL's Center for Semiconductor Modeling (CSM) of Materials and Devices has developed a fully quantum mechanical non-equilibrium Green’s function (NEGF) model that is able to accurately replicate the transport in real T2SL devices. The CSM subsequently used the model to predict the temperature dependence of the hole mobility in InAs/InAsSb T2SLs and validated the model against measured data. Leveraging this predictive capability, the CSM searched for new LWIR T2SL structures optimized for enhanced hole transport in the vertical direction. Specifically, we performed an extensive investigation over various substrate lattice constants from GaSb to InSb, searching for structures with high mobility despite T2SL disorder and found several promising structures that warrant further investigation.