Calculation of vertical and horizontal mobilities in InAs/GaSb superlattices

Superlattice (SL) devices such as infrared detectors and quantum-cascade lasers rely on efficient transport of carriers perpendicular to the SL layers by drift and/or diffusion. While horizontal mobilities are measured routinely, measurements of perpendicular-carrier mobilities require nonstandard experimental techniques such as the geometric magneto-resistance. Here we show how perpendicular mobilities can be estimated from horizontal mobility measurements and calculated mobilities. We treat low-temperature horizontal and vertical transport in SL on an equal footing by calculating both mobilities using the same interface roughness scattering (IRS) model from a rigorous solution of the Boltzmann transport equation. The calculation is specialized to the case of InAs/GaSb SLs, which are of current interest in the development of third-generation infrared detector focal plane arrays. The results are compared to available data.