We report magnetotransport measurements of InSb/Al1-xInxSb modulation doped quantum well
(QW) structures and the extracted transport ( ) tt and quantum (tq) lifetime of carriers at low
temperature (<2K.) We consider conventional transport lifetimes over a range of samples with
different doping levels and carrier densities, and deduce different transport regimes dependent on
QW state filling calculated from self-consistent Schrödinger–Poisson modelling. For samples
where only the lowest QW subband is occupied at electron densities of 2.13 10 ´ 11 cm−2 and
2.54 10 ´ 11 cm−2 quantum lifetimes of tq » 0.107 ps, and tq » 0.103 ps are extracted from
Shubnikov–de Haas oscillations below a magnetic field of 0.8 T. The extracted ratios of transport
to quantum lifetimes, t t t q » 17 and t t t q » 20 are similar to values reported in other binary
QW two-dimensional electron gas systems, but are inconsistent with predictions from transport
modelling which assumes that remote ionized donors are the dominant scattering mechanism.
We find the low t t t q ratio and the variation in transport mobility with carrier density cannot be
explained by reasonable levels of background impurities or well width fluctuations. Thus, there
is at least one additional scattering mechanism unaccounted for, most likely arising from
structural defects.