Influence of surface states on quantum and transport lifetimes in high-quality undoped heterostructures

Abstract

We present a comparison between experimental and theoretical values of transport ${\ensuremath{\tau}}_{t}$ and quantum ${\ensuremath{\tau}}_{q}$ scattering lifetimes in high-quality undoped Al${}_{0.34}$Ga${}_{0.66}$As/GaAs heterostructures. We obtain excellent agreement between the experimental and modeled scattering times using three scattering processes: background impurity, interface roughness, and remote ionized impurity scattering from surface states. We show that despite the high mobility (${\ensuremath{\mu}}_{\text{peak}}=5.6\ifmmode\times\else\texttimes\fi{}{10}^{6}\phantom{\rule{0.222222em}{0ex}}{\text{cm}}^{2}\phantom{\rule{0.16em}{0ex}}{\text{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\text{s}}^{\ensuremath{-}1}$), the quantum lifetime ${\ensuremath{\tau}}_{q}$ is significantly reduced by small-angle scattering from remote surface charge. We further show that in shallow devices scattering from surface charges will be a limiting factor for both transport and quantum lifetimes.