Kim, G H , Nicholls, James, Khondaker, S I , Farrer, I and Ritchie, D A (2000) Tuning the insulator-quantum Hall liquid transitions in a two-dimensional electron gas using self-assembled InAs. Physical Review B, 61 (16).
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We investigate the transport properties of two-dimensional electron gases (2DEGs) formed in a GaAs/Al(0.33)Ga(0.67)As quantum well, where InAs has been inserted into the center of the GaAs well. Depending on the growth conditions, the InAs forms either self-assembled quantum dots or dashes, and due to the resulting strain fields repulsive short-range scattering is experienced by the conduction electrons in the 2DEG. In a perpendicular magnetic field there are transitions between quantum Hall liquids at filling factors υ=1 and υ=2 and the insulating phase. Depending on the amount of InAs coverage, the degree of disorder in the 2DEG can be varied, changing the relative size of the υ=1 and υ=2 regions in the disorder-magnetic-field phase diagrams. Thermal studies show a spin gap at filling factor υ=1, which collapses as the magnetic field is decreased. Microscopic information about the dots was obtained from structural characterization, as well as from conductance measurements through individual dots isolated using a submicron split gate.
This is a Submitted version This version's date is: 15/4/2000 This item is not peer reviewed
https://repository.royalholloway.ac.uk/items/29ce3d89-344c-39de-1655-62742739c1e6/2/
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