Electronic transport in modulation-doped InSb quantum well heterostructures

Abstract

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 $51\text{ }000\text{ }{\text{cm}}^{2}/\text{V}\text{ }\text{s}$ are reported for heterostructures with a carrier concentration of $5.8\ifmmode\times\else\texttimes\fi{}{10}^{11}\text{ }{\text{cm}}^{\ensuremath{-}2}$, while low-temperature mobility (below 40 K) reaches $248\text{ }000\text{ }{\text{cm}}^{2}/\text{V}\text{ }\text{s}$ for a carrier concentration of $3.9\ifmmode\times\else\texttimes\fi{}{10}^{11}\text{ }{\text{cm}}^{\ensuremath{-}2}$. 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.