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.