Fabrication and characterization of ambipolar devices on an undoped AlGaAs/GaAs heterostructure

Chen, J. C. H.; Wang, D. Q.; Klochan, O.; Micolich, A. P.; Gupta, K. Das; Sfigakis, F.; Ritchie, D. A.; Reuter, D.; Wieck, A. D.; Hamilton, A. R.

doi:10.1063/1.3673837

Cited by 43 publications

(51 citation statements)

References 19 publications

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“…Similar discrepancies between electron and hole data have been noted in ref. [35]. Another possible scattering mechanism that must be kept in mind at high density is scattering between the electric subbands of the quantum well which is known to degrade the mobility in high density 2DESs.…”

Section: 11mentioning

confidence: 99%

Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells

et al. 2012

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We report on the growth and electrical characterization of a series of two-dimensional hole systems (2DHSs) used to study the density dependence of low temperature mobility in 20 nm GaAs/AlGaAs quantum wells. The hole density was controlled by changing the Al mole fraction and the setback of the delta-doping layer. We varied the density over a range from 1.8 × 10 10 cm −2 to 1.9 × 10 11 cm −2 finding a nonmonotonic dependence of mobility on density at T = 0.3 K. Surprisingly, a peak mobility of 2.3 × 10 6 cm 2 /Vs was measured at a density of 6.5 × 10 10 cm −2 with further increase in density resulting in reduced mobility. We discuss possible mechanisms leading to the observed non-monotonic density dependence of the mobility. Relying solely on interface roughness scattering to explain the observed drop in mobility at high density requires roughness parameters which are not consistent with measurements of similar electron structures. This leaves open the possibility of contributions from other scattering mechanisms at high density.Two-dimensional hole systems (2DHSs) on (001) oriented GaAs offer an interesting alternative to the more widely studied two-dimensional electron systems (2DESs). 2DHSs on (001) GaAs have effective masses roughly 4.5 to 7.5 times larger 1-3 than that in corresponding 2DESs which increases the importance of Coulomb interactions relative to the kinetic energy resulting in enhancement of importance of many-body effects. In addition, the p-wave symmetry of the valence band in GaAs leads to a much reduced hyperfine coupling of hole spins to the atomic nuclei which makes them an exciting alternative to electrons for quantum dot spinbased qubits [4][5][6] . The presence of spin-orbit coupling and light/heavy hole mixing in the valence band of GaAs also allows extensive band structure engineering 7-9 . This feature has been exploited to alter the nature of groundstates in the quantum Hall regime.

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Section: 11mentioning

confidence: 99%

Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells

et al. 2012

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“…The hole quantum dot is fabricated on a shallow undoped (100) GaAs/Al x Ga 1−x As heterostructure comprising a 10 nm GaAs cap and a 50 nm Al x Ga 1−x As layer on a GaAs buffer layer using the approach described in Ref [17]. Separate measurements of a 2D Hall bar device show the 2D holes have a mobility of 600, 000 cm 2 /Vs at p = 2.5 × 10 11 cm −2 and T = 250 mK.…”

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confidence: 99%

Double-layer-gate architecture for few-hole GaAs quantum dots

et al. 2016

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Article:Wang, D.Q., Hamilton, A.R., Farrer, I. orcid.org/0000-0002-3033-4306 et al. (2 more authors) (2016) Double-layer-gate architecture for few-hole GaAs quantum dots. Nanotechnology, 27 (33). https://doi.org/10.1088/0957-4484/27/33/334001 This is an author-created, un-copyedited version of an article accepted for publication/published in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0957-4484/27/33/334001. eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract. We report the fabrication of single and double hole quantum dots using a double-layer-gate design on an undoped accumulation mode AlxGa 1−x As/GaAs heterostructure. Electrical transport measurements of a single quantum dot show varying addition energies and clear excited states. In addition, the two-level-gate architecture can also be configured into a double quantum dot with tunable inter-dot coupling. † Present Address:

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“…Equally, ambipolar transport is also of much interest in fundamental studies of scattering, interaction and spin related phenomena since electrons and holes have very different effective masses, band structures and spin properties [1,2]. Chen et al [1] and Croxall et al [2] studied the density dependence of µ p and µ e in ambipolar GaAs/AlGaAs single heterojunction devices and quantum wells (QWs) respectively. The mobilities were found to depend not only on the …”

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Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

Taneja

Shlimak

Narayan

et al. 2017

J. Phys.: Condens. Matter

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Ambipolar transport, or the ability to switch between electrons and holes in the same device, has strong implications towards the implementation of functional devices: for instance, creating gate-defined n-and p-type conducting channels in the same device can be exploited in thermoelectric power generation, as well as towards spintronic applications by tuning between large (holes) and small (electrons) spinorbit coupling. Equally, ambipolar transport is also of much interest in fundamental studies of scattering, interaction and spin related phenomena since electrons and holes have very different effective masses, band structures and spin properties [1,2]. Chen et al [1] and Croxall et al [2] studied the density dependence of µ p and µ e in ambipolar GaAs/AlGaAs single heterojunction devices and quantum wells (QWs) respectively. The mobilities were found to depend not only on the AbstractWe report the results of an investigation of ambipolar transport in a quantum well of 15 nm width in an undoped GaAs/AlGaAs structure, which was populated either by electrons or holes using positive or negative gate voltage V tg , respectively. More attention was focussed on the low concentration of electrons n and holes p near the metal-insulator transition (MIT). It is shown that the electron mobility µ e increases almost linearly with increase of n and is independent of temperature T in the interval 0.3 K-1.4 K, while the hole mobility µ p depends non-monotonically on p and T. This difference is explained on the basis of the different effective masses of electrons and holes in GaAs. Intriguingly, we observe that at low p the source-drain current (I SD )-voltage (V) characteristics, which become non-linear beyond a certain I SD , exhibit a re-entrant linear regime at even higher I SD . We find, remarkably, that the departure and reappearance of linear behaviour are not due to non-linear response of the system, but due to an intrinsic mechanism by which there is a reduction in the net number of mobile carriers. This effect is interpreted as evidence of inhomogeneity of the conductive 2D layer in the vicinity of MIT and trapping of holes in 'dead ends' of insulating islands. Our results provide insights into transport mechanisms as well as the spatial structure of the 2D conducting medium near the 2D MIT.Keywords: non-linear I-V characteristics, two-dimensional hole gas, metal-insulator transition (Some figures may appear in colour only in the online journal)Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.1361-648X/17/185302+7$33.00

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Fabrication and characterization of ambipolar devices on an undoped AlGaAs/GaAs heterostructure

Cited by 43 publications

References 19 publications

Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells

Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells

Double-layer-gate architecture for few-hole GaAs quantum dots

Reappearance of linear hole transport in an ambipolar undoped GaAs/AlGaAs quantum well

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