For all panels, the chronological order of biased illuminations and symbols used are identical to that indicated in Fig. Nonreversibility of transport characteristics after biased illuminations on unipolar sample M (with only n-type Ohmic contacts). The inset in (d) has the same axes and units as in the main figure it is a magnified view of the data points near n 2D = 1.1 × 10 11 cm − 2. For clarity, only a selection of biased illuminations are shown in these panels. Electron mobilities after multiple biased illuminations are shown for a (c) shallow wafer G370 and (d) deep wafer G373. Note how the characteristics of the initial ‘0V’ biased illumination (red “ +” symbols) are recovered when another biased illumination at V topgate = 0 V is performed (black “ ×” symbols) after three biased illuminations are performed at V topgate = − 2, − 4, and − 6 V.

In all cases, the electron density versus topgate voltage relation is shifted by the voltage at which the biased illumination was performed.

Symbols in all four panels are defined in (c), and are in the order of biased illuminations performed during the same cooldown, with “start” being the first. 12Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo N2L 3G1, CanadaĮlectron density versus topgate voltage after multiple biased illuminations on (a) shallow wafer G370 and (b) deep wafer G373.11Security and Disruptive Technologies Research Centre, National Research Council of Canada, Ottawa, K1A 0R6, Canada.10Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom.9School of Physics, University of New South Wales, Sydney NSW 2052, Australia.8Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom.7Department of Electrical and Computer Engineering, University of Waterloo, Waterloo N2L 3G1, Canada.6Department of Physics and Astronomy, University of Waterloo, Waterloo N2L 3G1, Canada.5Department of Physics, Indian Institute of Technology Bombay, Mumbai 40007, India.4Northern Quantum Lights Inc., Waterloo N2B 1N5, Canada.3Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.2Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada.1Institute for Quantum Computing, University of Waterloo, Waterloo N2L 3G1, Canada.Experimental results are modeled with Boltzmann transport theory, and possible mechanisms are discussed.Ī. Remarkably, this mobility gain/loss is fully reversible by performing another biased illumination with the appropriate gate voltage, provided both n-type and p-type Ohmic contacts are present. The magnitude of the mobility gain (loss) weakens with 2DEG depth, and is likely driven by a reduction (increase) in surface charge density. Biased illuminations performed with positive applied gate voltages result in a mobility gain, whereas those performed with negative applied voltages result in a mobility loss. In 2DEGs closer to the surface, unbiased illuminations result in a mobility loss, driven by an increase in surface charge density. Unbiased illuminations in 2DEGs located more than 70 nm away from the surface result in a gain in mobility at a given electron density, primarily driven by the reduction of background impurities. Illumination is performed at low temperature on dopant-free two-dimensional electron gases (2DEGs) of varying depths, under unbiased (gates grounded) and biased (gates at a positive or negative voltage) conditions.

Illuminations org