Low temperature transport in undoped mesoscopic structures

Sarkozy, S.; Gupta, K. Das; Siegert, Christoph; Ghosh, Anirban; Pepper, M.; Farrer, I.; Beere, Harvey E.; Ritchie, D. A.; Jones, G. A. C.

doi:10.1063/1.3097806

Cited by 21 publications

(20 citation statements)

References 21 publications

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“…The second most important are the undesired background (bulk) impurities, which can have a density as low as 1 − 5 × 10 13 cm −3 [119,120], and cause most of the disorder in undoped systems [121]. Surface charges can also induce disorder, and mainly influence shallow (30 − 40 nm deep) 2DEGs.…”

Section: Reducing Disordermentioning

confidence: 99%

Quantum Dot Systems: a versatile platform for quantum simulations

Barthelemy

Vandersypen

2013

Annalen der Physik

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Quantum mechanics often results in extremely complex phenomena, especially when the quantum system under consideration is composed of many interacting particles. The states of these many-body systems live in a space so large that classical numerical calculations cannot compute them. Quantum simulations can be used to overcome this problem: complex quantum problems can be solved by studying experimentally an artificial quantum system operated to simulate the desired hamiltonian.Quantum dot systems have shown to be widely tunable quantum systems, that can be efficiently controlled electrically. This tunability and the versatility of their design makes them very promising quantum simulators. This paper reviews the progress towards digital quantum simulations with individually controlled quantum dots, as well as the analog quantum simulations that have been performed with these systems. The possibility to use large arrays of quantum dots to simulate the low-temperature Hubbard model is also discussed. The main issues along that path are presented and new ideas to overcome them are proposed.

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Section: Reducing Disordermentioning

confidence: 99%

Quantum Dot Systems: a versatile platform for quantum simulations

Barthelemy

Vandersypen

2013

Annalen der Physik

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“…Fig. 3 a & 3b [3,4,5] show the two known methods of making undoped 2DEGs. However a structure of the type shown in Fig.…”

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confidence: 99%

“…3a cannot be made very shallow, because the ohmic material (after annealing) is rough and . We have used a two level gating scheme [4,5], (see Fig. 3b) to define point contacts and quantum dots on this wafer(data not shown).…”

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confidence: 99%

Ultra-shallow undoped 2DEGs in GaAs-AlGaAs heterostructures

Gupta¹,

Mak²,

Sfigakis³

et al. 2011

AIP Conference Proceedings

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Strain-less directed self-assembly of Si nanocrystals on patterned SiO2 substrate J. Appl. Phys. 112, 054311 (2012) Wall-liquid and wall-crystal interfacial free energies via thermodynamic integration: A molecular dynamics simulation study J. Chem. Phys. 137, 044707 (2012) The influence of the atomic interactions in out-of-plane on surface energy and its applications in nanostructures J. Appl. Phys. 112, 013524 (2012) Energetic instability of polygonal micro-and nanowires J. Appl. Phys. 111, 103509 (2012) Stability of nano-scale ferroelectric domains in a LiNbO3 single crystal: The role of surface energy and polar molecule adsorption

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“…Device yield is often low and the devices can suffer from high contact resistance. Another FET design reported in the literature utilizes a lithographically-defined global top-gate deposited on top of insulators such as polyimides [17,[19][20]23], nitrides [24,25] or oxides [26] separating the ohmic contacts from the gate. In this configuration the global top-gate must extend over the ohmic contact pad to ensure a continuous 2DEG to the ohmic contact.…”

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confidence: 99%

“…Field-effect-induced 2DEG transistors (FETs) in GaAs/AlGaAs heterostructures have been investigated extensively [14][15][16][17][18][19][20][21][22][23][24][25][26][27] and might find utility as a platform to investigate nanoscale phenomena in a low-noise environment if certain limitations can be overcome. The most widely studied device is the heterostructure-insulated-gate field-effect transistor (HIGFET), in which a highly-conducting n+ GaAs gate is grown on top of an insulating Al x Ga 1−x As barrier layer by molecular beam epitaxy (MBE) [14-16, 18, 22].…”

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confidence: 99%

Field-effect-induced two-dimensional electron gas utilizing modulation-doped ohmic contacts

Mondal

Gardner

Watson

et al. 2014

Solid State Communications

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Modulation-doped AlGaAs/GaAs heterostructures are utilized extensively in the study of quantum transport in nanostructures, but charge fluctuations associated with remote ionized dopants often produce deleterious effects. Electric field-induced carrier systems offer an attractive alternative if certain challenges can be overcome. We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate reliable lowresistance contacts. A high quality two-dimensional electron gas is induced by a field-effect and is tunable over a wide range of density. Device design, fabrication, and low temperature (T= 0.3K) transport data are reported.Nanostructures such as quantum point contacts and quantum dots fabricated on modulation-doped AlGaAs/GaAs heterostructures are widely used to explore nanoscale electron transport and are utilized extensively in spin-based approaches to quantum computing [1][2][3][4][5][6][7][8]. Modulation-doped GaAs/AlGaAs heterostructures possess several desirable attributes including very high mobility of the underlying two-dimensional electron gas (2DEG) and the relative ease of nanostructure fabrication. However, the presence of ionized dopants inherent to modulationdoping can have adverse effects on the behavior of nanostructures and are a possible source of decoherence for spin-qubits [9,10]. Ionized dopants can act as active trapping sites for electrons injected from the metal surface gate through the Schottky barrier [11], giving rise to random switching of the charge state of the impurities. These fluctuations cause instability through a time-dependent potential landscape [10][11][12][13]. Methods such as 'bias cooling' in which nanostructures are cooled while a positive bias applied to the gates aid in reducing fluctuations [11], but charge noise is still believed to a dominant mechanism limiting gate fidelities in spin qubits [9].

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Low temperature transport in undoped mesoscopic structures

Cited by 21 publications

References 21 publications

Quantum Dot Systems: a versatile platform for quantum simulations

Quantum Dot Systems: a versatile platform for quantum simulations

Ultra-shallow undoped 2DEGs in GaAs-AlGaAs heterostructures

Field-effect-induced two-dimensional electron gas utilizing modulation-doped ohmic contacts

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