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arXiv · 1804.06936

Mobility and quantum mobility of modern GaAs/AlGaAs heterostructures

M. Sammon·M. A. Zudov·B. I. Shklovskii
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Abstract

In modern GaAs/Al$_x$Ga$_{1-x}$As heterostructures with record high mobilities, a two-dimensional electron gas (2DEG) in a quantum well is provided by two remote donor $δ$-layers placed on both sides of the well. Each $δ$-layer is located within a narrow GaAs well, flanked by narrow AlAs layers which capture excess electrons from donors. We show that each excess electron is localized in a compact dipole atom with the nearest donor. Nevertheless, excess electrons screen both the remote donors and background impurities. When the fraction of remote donors filled by excess electrons $f$ is small, the remote donor limited quantum mobility grows as $f^{3}$ and becomes larger than the background impurity limited one at a characteristic value $f_c$. We also calculate both the mobility and the quantum mobility limited by the screened background impurities with concentrations $N_1$ in Al$_x$Ga$_{1-x}$As and $N_2$ in GaAs, which allows one to estimate $N_1$ and $N_2$ from the measured mobilities. Taken together, our findings should help to identify avenues for further improvement of modern heterostructures.

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M. Sammon, M. A. Zudov, B. I. Shklovskii. 2018-07-12. Mobility and quantum mobility of modern GaAs/AlGaAs heterostructures. https://doi.org/10.1103/physrevmaterials.2.064604

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