Temperature dependent Hall effect in InAsSb with a 0.11 eV 77 K-bandgap

InAsSb is the only direct-bandgap III-V compound semiconductor alloy that absorbs and emits light over the entire long-wavelength infrared band (8-12 micron). We measured its free electron concentration and mobility as a function of temperature in materials with a 77 K-bandgap of 0.11 eV and compared the results with those of the II-VI compound, HgCdTe. The intrinsic electron concentration exhibits an expected freeze-out, which can be described with Fermi statistical electron and hole distributions, taking into account the non-parabolicity of the conduction band and the temperature dependence of the bandgap. Using known values for the electron mass, the heavy hole mass is estimated to be 0.4m₀. The background concentration is n-type and is caused by a donor resonant with the conduction band of ∼8.7 meV above its bottom. The electron mobility exhibits a noticeably different behavior compared with HgCdTe. Between room temperature and ∼77 K, the InAsSb mobility is significantly higher, indicating a difference in phonon scattering, while at lower temperatures where alloy and impurity scattering dominate, the mobility of the unoptimized InAsSb is lower.