Probing the sensitivity of electron wave interference to disorder-induced scattering in solid-state devices

Scannell, B. C.; Pilgrim, Ian; See, A. M.; Montgomery, Rick; Morse, Peter K.; Fairbanks, M. S.; Marlow, C. A.; Linke, Heiner; Farrer, I.; Ritchie, D. A.; Hamilton, A. R.; Micolich, A. P.; Eaves, L.; Taylor, R. P.

doi:10.1103/physrevb.85.195319

Cited by 9 publications

(27 citation statements)

References 61 publications

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“…This brings benefits such as enhanced robustness of the 5/2 fractional quantum Hall state, 8 and improved experimental access to the metallic state generated by electron-electron interactions in 2D systems. 17 Second, the absence of intentional ionized impurities gives electrical properties that are remarkably robust to thermal cycling 18 , in stark contrast to modulation-doped heterostructures 6 . Both features demonstrate there is much more to disorder than the popular metric of mobility alone.…”

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confidence: 99%

Using light and heat to controllably switch and reset disorder configuration in nanoscale devices

et al. 2015

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Quantum dots exhibit reproducible conductance fluctuations at low temperatures due to electron quantum interference. The sensitivity of these fluctuations to the underlying disorder potential has only recently been fully realized. We exploit this sensitivity to obtain a novel tool for better understanding the role that background impurities play in the electrical properties of high-mobility AlGaAs/GaAs heterostructures and nanoscale devices. In particular, we report the remarkable ability to first alter the disorder potential in an undoped AlGaAs/GaAs heterostructure by optical illumination and then reset it back to its initial configuration by room temperature thermal cycling in the dark. We attribute this behavior to a mixture of C background impurities acting as shallow acceptors and deep trapping by Si impurities. This 'alter and reset' capability, not possible in modulation-doped heterostructures, offers an exciting route to studying how scattering from even small densities of charged impurities influences the properties of nanoscale semiconductor devices.Disorder is an important issue in nanoelectronics; as a device is reduced in size it becomes more sensitive to temporal fluctuations and spatial inhomogeneities in the charged impurity distribution.1 The temporal fluctuations cause decoherence 2,3 , noise 4 and device irreproducibility. 5,6 These are troublesome for the development of quantum applications for semiconductor devices. Spatial inhomogeneities interrupt electron flow 7 adversely affecting 8 practical realization of concepts such as topological quantum computation using the 5/2 fractional quantum Hall state 9 . These barriers to applications have fueled research to reduce, control and better understand disorder in nanoscale electronic devices.Approaches to disorder reduction for nanoscale devices include modulation-doping 10 , short period superlattice doping 11,12 , and undoped heterostructures where the carriers are induced using either a metal 13,14 or degenerately-doped semiconductor gate 15,16 . While modulation-doped structures still provide the highest mobilities, undoped heterostructures provide two distinct advantages. First, short range neutral disorder dominates over long range Coulombic disorder. This brings benefits such as enhanced robustness of the 5/2 fractional quantum Hall state, 8 and improved experimental access to the metallic state generated by electron-electron interactions in 2D systems.17 Second, the absence of intentional ionized impurities gives electrical properties that are remarkably robust to thermal cycling 18 , in stark contrast to modulation-doped heterostructures 6 . Both features demonstrate there is much more to disorder than the popular metric of mobility alone.19 They also strongly motivate the quest for a deeper understanding of the nature of disorder in undoped heterostructure devices. a) Electronic mail: adam.micolich@nanoelectronics.physics.unsw.edu.auWe recently developed a novel approach to studying disorder in nanoscale devices. It relies on the fact...

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Using light and heat to controllably switch and reset disorder configuration in nanoscale devices

et al. 2015

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“…36 If an n-type heterostructure is warmed above ∼ 120 K, the DX centers begin releasing their electrons allowing the doping layer charge distribution to change. 37,50,51 This provides an ideal system for studying whether charge motion in the doping layer generates hysteresis similar to that observed for p-type heterostructures. Gate hysteresis data from Device D at T = 120 and 130 K is shown in Figure 5(a/b).…”

Section: Evidence For the Role Of Dopantsmentioning

confidence: 99%

“…This 'freezing' dopant layer charge is vital to the stability and reproducibility of the electronic properties of devices based on Si-doped n-type AlGaAs/GaAs heterostructures at low temperatures. 37,51,52 Comparatively little is known about the defect physics of Si dopants in (311)-oriented p-type AlGaAs/GaAs heterostructures. In addition to acting as a simple substitutional acceptor by occupying an As site, Si has also been suggested to form an acceptor complex/deep trap known as Si-X.…”

Section: Possible Explanations For This Form Of Hysteresismentioning

confidence: 99%

“…Hence our third approach was to investigate dopant effects through variable temperature studies. In particular, we compare the hysteresis in hole devices to electron devices at elevated temperatures T ∼ 130 K, where deep donors known as DX centers 36 begin to detrap, 37 allowing charge to migrate between Si dopant sites. We observe gate hysteresis in electron devices at 130 K very similar to that in hole devices at T < 4 K. We also show that the hysteresis can be reduced in hole devices by reducing the thickness of the dopant layer from 80 nm to less than 5 nm (δ-doped).…”

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The origin of gate hysteresis in p-type Si-doped AlGaAs/GaAs heterostructures

et al. 2012

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Gate instability/hysteresis in modulation-doped p-type AlGaAs/GaAs heterostructures impedes the development of nanoscale hole devices, which are of interest for topics from quantum computing to novel spin physics. We present an extended study conducted using custom-grown, matched modulation-doped n-type and p-type heterostructures, with/without insulated gates, aimed at understanding the origin of the hysteresis. We show the hysteresis is not due to the inherent 'leakiness' of gates on p-type heterostructures, as commonly believed. Instead, hysteresis arises from a combination of GaAs surface-state trapping and charge migration in the doping layer. Our results provide insights into the physics of Si acceptors in AlGaAs/GaAs heterostructures, including widely-debated acceptor complexes such as Si-X. We propose methods for mitigating the gate hysteresis, including poisoning the modulation-doping layer with deep-trapping centers (e.g., by co-doping with transition metal species), and replacing the Schottky gates with degenerately-doped semiconductor gates to screen the conducting channel from GaAs surface-states.

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“…Ballistic, non-dephasing, electrons are essential for interferometric devices which probe the phase differences along different pathways. [7][8][9] Here, we investigate to what extent the ballistic description reproduces experimental data in multi-terminal devices, where the branching ratio of the thermal energy current is varied by applying a top-gate voltage. 10 In previous quasi-one-dimensional transport studies, thermal conductance in multiples of the theoretical quantum limit 11 κ = k 2 B π 3 T has been observed.…”

Section: Introductionmentioning

confidence: 99%

Thermal energy and charge currents in multi-terminal nanorings

et al. 2016

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We study in experiment and theory thermal energy and charge transfer close to the quantum limit in a ballistic nanodevice, consisting of multiply connected one-dimensional electron waveguides. The fabricated device is based on an AlGaAs/GaAs heterostructure and is covered by a global top-gate to steer the thermal energy and charge transfer in the presence of a temperature gradient, which is established by a heating current. The estimate of the heat transfer by means of thermal noise measurements shows the device acting as a switch for charge and thermal energy transfer. The wave-packet simulations are based on the multi-terminal Landauer-Büttiker approach and confirm the experimental finding of a mode-dependent redistribution of the thermal energy current, if a scatterer breaks the device symmetry.

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Probing the sensitivity of electron wave interference to disorder-induced scattering in solid-state devices

Cited by 9 publications

References 61 publications

Using light and heat to controllably switch and reset disorder configuration in nanoscale devices

Using light and heat to controllably switch and reset disorder configuration in nanoscale devices

The origin of gate hysteresis in p-type Si-doped AlGaAs/GaAs heterostructures

Thermal energy and charge currents in multi-terminal nanorings

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