Effect of illumination on quantum lifetime in GaAs quantum wells

Fu, Xu; Riedl, Austin D.; Borisov, M. M.; Zudov, M. A.; Watson, John; Gardner, G. C.; Manfra, Michael J.; Baldwin, K. W.; Pfeiffer, L. N.; West, K. W.

doi:10.1103/physrevb.98.195403

Cited by 10 publications

(6 citation statements)

References 33 publications

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“…Once again, one can see that the observed growth of

as a function of

cannot be described over the full interval by a linear function, i.e.,

, which implies that a more complex mechanism governs this process—it is not just a strong interband absorption with one type of impurities involved [ 31 , 32 ]. One possible mechanism may be described as follows: (i) the VIS light is strongly absorbed in the AlGaAs barrier layers and produces electron-hole pairs near the δ-doping layers containing DX centers; (ii) some of the photo-generated holes are captured by DX centers, change their charge states and consequently create a periodic distribution of immobile positive charges in the δ-doping layers with a periodic spatial distribution that follows the light pattern; (iii) the unpaired free electrons drift towards and are eventually captured by the QW increasing

of the 2DEG.…”

Section: Resultsmentioning

confidence: 99%

“…Once again, one can see that the observed growth of 𝑛 as a function of 𝐹 cannot be described over the full interval by a linear function, i.e., f3 = 1.685 + 3.2 × 10 𝐹, which implies that a more complex mechanism governs this process-it is not just a strong interband absorption with one type of impurities involved [31,32]. One possible mechanism may be described as follows: (i) the VIS light is strongly absorbed in the AlGaAs barrier layers and produces electron-hole pairs near the δ-doping layers containing DX centers; 7a; n s = 2.16 × 10 11 cm −2 according to the data point 5 in Figure 7b.…”

Section: Hall Bar Illumination At λ 1 = 637 Nmmentioning

confidence: 99%

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An Optical Technique to Produce Embedded Quantum Structures in Semiconductors

et al. 2023

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The performance of a semiconductor quantum-electronic device ultimately depends on the quality of the semiconductor materials it is made of and on how well the device is isolated from electrostatic fluctuations caused by unavoidable surface charges and other sources of electric noise. Current technology to fabricate quantum semiconductor devices relies on surface gates which impose strong limitations on the maximum distance from the surface where the confining electrostatic potentials can be engineered. Surface gates also introduce strain fields which cause imperfections in the semiconductor crystal structure. Another way to create confining electrostatic potentials inside semiconductors is by means of light and photosensitive dopants. Light can be structured in the form of perfectly parallel sheets of high and low intensity which can penetrate deep into a semiconductor and, importantly, light does not deteriorate the quality of the semiconductor crystal. In this work, we employ these important properties of structured light to form metastable states of photo-sensitive impurities inside a GaAs/AlGaAs quantum well structure in order to create persistent periodic electrostatic potentials at large predetermined distances from the sample surface. The amplitude of the light-induced potential is controlled by gradually increasing the light fluence at the sample surface and simultaneously measuring the amplitude of Weiss commensurability oscillations in the magnetoresistivity.

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“…Once again, one can see that the observed growth of

as a function of

cannot be described over the full interval by a linear function, i.e.,

of the 2DEG.…”

Section: Resultsmentioning

confidence: 99%

Section: Hall Bar Illumination At λ 1 = 637 Nmmentioning

confidence: 99%

An Optical Technique to Produce Embedded Quantum Structures in Semiconductors

et al. 2023

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“…Their samples use a delta-doping scheme that places Si dopants in GaAs "doping" wells [57,78], thus preventing the formation of DX centers. The improvement of their FQHE states after illumination is attributed to enhanced screening from dopant-dopant correlations [74,79], in a manner very reminiscent of overdoping [78]. Could dopant-dopant correlations occur in dopant-free 2DEGs?…”

Section: Discussionmentioning

confidence: 99%

Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs

et al. 2022

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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 n-type and p-type Ohmic contacts are present. Experimental results are modeled with Boltzmann transport theory, and possible mechanisms are discussed.

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“…Ultra-high-quality samples with much longer τ q , such as those in Refs. [33,36], might be necessary to observe the predicted screening effect on τ q . Yet, it is interesting that the visibility of the spin gap varies with n SL /N Si even when τ q remains constant, as we observed.…”

Section: Quantum Lifetimementioning

confidence: 99%

Screening effects of superlattice doping on the mobility of GaAs two-dimensional electron system revealed by in-situ gate control

Akiho,

Muraki

2021

Preprint

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We investigate the screening effects of excess electrons in the doped layer on the mobility of a GaAs twodimensional electron system (2DES) with a modern architecture using short-period superlattice (SL) doping. By controlling the density of excess electrons in the SL with a top gate while keeping the 2DES density constant with a back gate, we are able to compare 2DESs with the same density but different degrees of screening using one sample. Using a field-penetration technique and circuit-model analysis, we determine the density of states and excess electron density in the SL, quantities directly linked to the screening capability. The obtained relation between mobility and excess electron density is consistent with the theory taking into account the screening by the excess electrons in the SL. The quantum lifetime determined from Shubnikov-de Haas oscillations is much lower than expected from theory and did not show a discernible change with excess electron density.

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Effect of illumination on quantum lifetime in GaAs quantum wells

Cited by 10 publications

References 33 publications

An Optical Technique to Produce Embedded Quantum Structures in Semiconductors

An Optical Technique to Produce Embedded Quantum Structures in Semiconductors

Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs

Screening effects of superlattice doping on the mobility of GaAs two-dimensional electron system revealed by in-situ gate control

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