Electronic transport in modulation-doped InSb quantum well heterostructures

The mobility and carrier concentration of a number of InSb-based modulation-doped quantum well heterostructures are examined over a range of temperatures between 4.5 and 300 K. Wide well (30 nm) and narrow well (15 nm) structures are measured. The temperature dependent mobilities are considered within a scattering model that incorporates polar optical and acoustic phonon scatterings, interface roughness scattering, and scattering from charged impurities both in the three-dimensional background and within a distributed ``quasi-two-dimensional'' doping layer. Room temperature mobilities as high as 51 000 cm²/V s are reported for heterostructures with a carrier concentration of 5.8×10¹¹ cm^-2, while low-temperature mobility (below 40 K) reaches 248 000 cm²/V s for a carrier concentration of 3.9×10¹¹ cm^-2. A Schr\"odinger--Poisson model is used to calculate band structures in the material and is shown to accurately predict carrier concentrations over the whole temperature range. Low-temperature mobility is shown to be dominated by remote ionized impurity scattering in wide well samples and by a combination of ionized impurity and interface roughness scattering in narrow well samples.