Calculation of the temperature dependence of the vertical and horizontal mobilities in InAs/GaSb superlattices

In order to limit cooling requirements, it is important to operate superlattice devices such as infrared detectors at the highest possible temperatures consistent with maintaining satisfactory figures of merit regarding signal and noise. One of the characteristics governing the device performance is vertical carrier mobility, although only horizontal mobilities are routinely measured. Recently, we calculated low-temperature vertical and horizontal mobilities, as limited by interface roughness scattering, for type-II InAs/GaSb superlattices as a function of SL dimensions and the degree of roughness. We found that the horizontal mobility was a double-valued function of the roughness correlation length, Λ. Here, we show that the indeterminacy of Λ can be overcome by comparing the temperature dependence of the calculated and measured mobilities; hence, we extend the calculation to higher temperatures. While the scattering mechanism itself is temperature independent, the band structure and the carrier distribution are temperature-dependent. As a function of temperature, we find that as a function of the correlation length, mobilities can increase, decrease, or remain constant. This behavior is explained on the basis of the physics of the problem.