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(Color online) Typical Hall data set from which we extract μ = 96 000 cm2/Vs and n = 2.5 × 1011/cm2. Wafer details are given in main text. Horizontal lines indentify the visible quantum Hall plateaus. Upper left inset: Heterostructure growth profile. Upper right inset: Hall bar geometry with dimensions given in microns.
(Color online) (a) Carrier mobility plotted as a function of charge density for each wafer series. (b) Hall data sets recorded before and after illumination with a LED for a series 2 wafer with a doping level of 3 × 1018/cm3, resulting in μ = 30 000 cm2/Vs and n = 1.8 × 1011/cm2 before illumination and μ = 49 000 cm2/Vs and n = 2.4 × 1011/cm2 after illumination. (c) A series 1 wafer (5 nm spacer) with a doping level of 6 × 1017/cm3 does not show clear zeros in ρxx after illumination with a LED. μ = 48 000 cm2/Vs and n = 3.7 × 1011/cm2 for this sample.
(Color online) (a) Colorscale plot of quantum dot conductance, g, as a function of Vg and VSD . Clear Coulomb diamonds are observed when the device is configured as a single dot. Inset: Conductance as a function of Vg for VSD = 0. (b) Derivative of the charge sensor conductance, dgS /dVL , measured as a function of VL and VR . Black transitions (negative slopes) correspond to charge transitions that change the total number of electrons, while yellow transitions (positive slopes) correspond to interdot charge transitions. Inset: Scanning electron micrograph of a double quantum dot similar to the one measured.
Layer thicknesses for the three different heterostructure growth profiles studied in this report.
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