Abstract:
The question whether alloy disorder is screened or unscreened is of fundamental
importance. Therefore, we calculate the mobility of the interacting
two-dimensional electron gas
as realized in Al$_x$Ga$_{1-x}$As quantum wells and heterostructures in the presence of alloy-disorder
scattering. For the screening we use the random-phase approximation and we include many-body
effects due to exchange and correlation. We propose to determine the alloy disorder potential $V_{\text{AD}}$
from mobility measurements. If we use $V_{\text{AD}}=1.04\,$eV we can explain recent experimental
results obtained for quantum wells and heterostructures with ultrahigh mobility. From the
anomalous linear temperature dependence of the mobility measured in heterostructures we
conclude that the alloy disorder is screened. More experiments are needed to confirm the
screening of the alloy disorder and we propose some measurements.
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