Shetty, A;
Sfigakis, F;
Mak, WY;
Das Gupta, K;
Buonacorsi, B;
Tam, MC;
Kim, HS;
... Baugh, J; + view all
(2022)
Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs.
Physical Review B
, 105
(7)
, Article 075302. 10.1103/PhysRevB.105.075302.
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Abstract
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. 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. In 2DEGs closer to the surface, unbiased illuminations result in a mobility loss, driven by an 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. The magnitude of the mobility gain (loss) weakens with 2DEG depth, and is likely driven by a reduction (increase) in surface charge density. Remarkably, this mobility gain/loss is fully reversible by performing another biased illumination with the appropriate gate voltage, provided both Formula Presented-type and Formula Presented-type Ohmic contacts are present. Experimental results are modeled with Boltzmann transport theory, and possible mechanisms are discussed.
| Type: | Article |
|---|---|
| Title: | Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevB.105.075302 |
| Publisher version: | https://doi.org/10.1103/PhysRevB.105.075302 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10144554 |
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