Scattering mechanisms in state-of-the-art GaAs/AlGaAs quantum wells

Abstract

Motivated by recent breakthrough in molecular beam epitaxy of GaAs/AlGaAs quantum wells [Y. J. Chung \textit{et al.}, Nature Materials \textbf{20}, 632 (2021)], we examine contributions to mobility and quantum mobility from various scattering mechanisms and their dependencies on the electron density. We find that at lower electron densities, $n_e\lesssim 1\times 10^{11}$ cm${}^{-2}$, both transport and quantum mobility are limited by unintentional background impurities and follow a power law dependence, $\propto n_e^{\alpha }$, with $\alpha \approx 0.85$. Our predictions for quantum mobility are in reasonable agreement with an estimate obtained from the resistivity at filling factor $\nu =1/2$ in a sample of Y. J. Chung \textit{et al.} with $n_e=1\times 10^{11}$ cm${}^{-2}$. Consideration of other scattering mechanisms indicates that interface roughness (remote donors) is a likely limiting factor of transport (quantum) mobility at higher electron densities. Future measurements of quantum mobility should yield information on the distribution of background impurities in GaAs and AlGaAs.

4 pages, 3 figures + 3 pages supplementary materials

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