Invited Review Electronic properties of nanostructures defined in Ga[Al]As heterostructures by local oxidation

Fuhrer, Andreas; Dorn, August; Lüscher, Silvia; Heinzel, T.; Ensslin, Klaus; Wegscheider, Werner; Bichler, Max

doi:10.1006/spmi.2002.1015

Cited by 75 publications

(49 citation statements)

References 70 publications

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“…The 2DEG has a density of n s = 5 × 10 15 m −2 and a mobility of µ = 40 m 2 /Vs at 4.2 K. The double quantum dot structure has been predefined by local anodic oxidation [12] at room temperature. With this technique oxide lines are formed on the surface, below which the 2DEG is locally depleted.…”

Section: Sample and Setupmentioning

confidence: 99%

Spatial mapping and manipulation of two tunnel-coupled quantum dots

et al. 2011

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The metallic tip of a scanning force microscope operated at 300 mK is used to locally induce a potential in an fully controllable double quantum dot defined via local anodic oxidation in a GaAs/AlGaAs heterostructure. Using scanning gate techniques we record spatial images of the current through the sample for different numbers of electrons on the quantum dots, i.e. for different quantum states. Owing to the spatial resolution of current maps, we are able to determine the spatial position of the individual quantum dots, and investigate their apparent relative shifts due to the voltage applied to a single gate.

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Section: Sample and Setupmentioning

confidence: 99%

Spatial mapping and manipulation of two tunnel-coupled quantum dots

et al. 2011

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“…Details about the fabrication process can be found in Ref. 19. The two-dimensional electron gas is depleted below the oxide lines.…”

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confidence: 99%

Single-electron effects in a coupled dot-ring system

et al. 2004

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Aharonov-Bohm oscillations are studied in the magnetoconductance of a micron-sized open quantum ring coupled capacitively to a Coulomb-blockaded quantum dot. As the plunger gate of the dot is modulated and tuned through a conductance resonance, the amplitude of the Aharonov -Bohm oscillations in the transconductance of the ring displays a minimum. We demonstrate that the effect is due to a single-electron screening effect, rather than to dephasing. Aharonov-Bohm oscillations in a quantum ring can thus be used for the detection of single charges.Coupled mesoscopic systems are on top of the agenda for experimentalists trying to achieve charge read-out, controlled interference, and entanglement of electrons in magnetotransport experiments. In general, there are two limiting cases how coupling can be achieved: it can either be realized by pure electrostatic interaction without the overlap of wavefunctions of the systems to be coupled [1,2,3,4,5], or by tunnel coupling involving strong wavefunction overlap and limited electrostatic interaction. A number of experiments employed a quantum point contact as a non-invasive probe to detect the charge state of single or double quantum dots by way of electrostatic coupling between the two mesoscopic systems [6,7,8,9,10,11]. Furthermore, a quantum point contact has been used as a detector of the charge state of an antidot [12]. However, in mesoscopic systems where the phase coherence of at least one of the two electrostatically coupled partners is important, additional considerations such as dephasing due to quantum measurement have to be taken into account. Examples of such systems are tunnel coupled double dots [9,10,11] and quantum dots in the Kondo regime [8,13]. These experiments focus on the coupling between quantum dots, or the read-out of a (coupled) quantum dot system via a nearby quantum point contact.Our experiments study the coupling of a quantum dot to a ring, in which the occurrence of Aharonov-Bohm (AB) oscillations relies on the phase-coherence of the electrons. Ring-like geometries allow the observation of the interference of partial waves as a function of magnetic field, i.e., the AB effect [14,15,16,17], and information about electron decoherence can be extracted [16,17]. A mesoscopic detector situated nearby is expected to reduce the phase coherent AB oscillation amplitude [1]. Such a 'which path' experiment has been performed by Buks and coworkers, who coupled a quantum dot embedded in one arm of an AB interferometer electrostatically to a quantum point contact [18].Here we report on two electrostatically coupled quantum structures, namely, an AB ring and a Coulombblockaded quantum dot. The goal of the experiment is to detect the interaction between the two subsystems and to unravel its consequences. We show that single-electron charging in the quantum dot can be detected through a reduced AB oscillation amplitude in the transconductance of the ring. We find that our experimental observations are explained by a single-electron screening effect.The coupled...

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“…The isolating properties of oxide lines on GaAlAs/GaAs heterostructures can be described by Hartree calculations in accordance with experimental findings [7,8]. Using a simple model for the shape of the surface disturbance, the depletion …”

Section: Discussionmentioning

confidence: 65%

Self-Consistent potential calculation for locally oxidized Ga[Al]As heterostructures

May

Ensslin

Troyer

2007

J Computer-Aided Mater Des

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We simulate the influence of local oxidation with an atomic force microscope (AFM) tip on the surface of a GaAlAs/GaAs heterostructure by means of numerical calculations. Assuming a rectangular shape of the oxide line, we solve the Schrödinger and Poisson equations self-consistently on a two-dimensional surface perpendicular to the oxide line. We observe that the distance between the two-dimensional electron gas (2DEG) and the surface is a crucial parameter for the electron density, confirming experimental 2DEG depletion results.

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Invited Review Electronic properties of nanostructures defined in Ga[Al]As heterostructures by local oxidation

Cited by 75 publications

References 70 publications

Spatial mapping and manipulation of two tunnel-coupled quantum dots

Spatial mapping and manipulation of two tunnel-coupled quantum dots

Single-electron effects in a coupled dot-ring system

Self-Consistent potential calculation for locally oxidized Ga[Al]As heterostructures

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