Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates

MacLeod, Sarah J.; See, A. M.; Hamilton, A. R.; Farrer, I.; Ritchie, D. A.; Ritzmann, Julian; Ludwig, Arne; Wieck, A. D.

doi:10.1063/1.4905210

Cited by 10 publications

(7 citation statements)

References 32 publications

(30 reference statements)

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“…The aluminium is deposited in an arsenic-depleted ambience. b In the molecular beam epitaxy chamber used here, the background impurity concentration is estimated to be ~ 5 × 10 14 cm −3 for Al 0.33 Ga 0.67 As layers 50 . The doping concentration is around 2 × 10 18 cm −3 for the n + layer, while for p + and p ++ layers, it is around 2 × 10 18 cm −3 and 8 × 10 18 cm −3 , respectively.…”

Section: Resultsmentioning

confidence: 99%

Low-noise GaAs quantum dots for quantum photonics

et al. 2020

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Quantum dots are both excellent single-photon sources and hosts for single spins. This combination enables the deterministic generation of Raman-photons—bandwidth-matched to an atomic quantum-memory—and the generation of photon cluster states, a resource in quantum communication and measurement-based quantum computing. GaAs quantum dots in AlGaAs can be matched in frequency to a rubidium-based photon memory, and have potentially improved electron spin coherence compared to the widely used InGaAs quantum dots. However, their charge stability and optical linewidths are typically much worse than for their InGaAs counterparts. Here, we embed GaAs quantum dots into an n-i-p-diode specially designed for low-temperature operation. We demonstrate ultra-low noise behaviour: charge control via Coulomb blockade, close-to lifetime-limited linewidths, and no blinking. We observe high-fidelity optical electron-spin initialisation and long electron-spin lifetimes for these quantum dots. Our work establishes a materials platform for low-noise quantum photonics close to the red part of the spectrum.

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Section: Resultsmentioning

confidence: 99%

Low-noise GaAs quantum dots for quantum photonics

et al. 2020

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“…The MBE aluminum FET has a double‐gate structure, which enables control of the density in the channel and the ohmic contacts separately. [ 17,28 ] The first control FET was fabricated by wet‐etching the MBE‐grown aluminum away, and then evaporating an aluminum gate onto the wafer surface in a standard thermal evaporator (see “device structure” Figure 2b). The second control transistor has a metal‐oxide FET architecture; the MBE‐grown aluminum was etched away and a 25 nm aluminum oxide layer (AlO x ) was deposited by atomic layer deposition (ALD).…”

Section: Resultsmentioning

confidence: 99%

“…This approach resulted in a marked increase in 2DEG mobility due to the reduction of surface charge. [ 15–17 ] Despite successfully minimizing unwanted effects of surface charge, this approach has limitations; patterning increasingly finer structures on the doped semiconductor gate leads to charge depletion in the nano‐patterned gate, which causes the gate to become insulating and non‐functional. An alternative option is to use an MBE‐grown epitaxial aluminum gate (Figure 1b), which has a much smaller depletion length than the heavily doped semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐Shallow All‐Epitaxial Aluminum Gate GaAs/Al_xGa_1−xAs Transistors with High Electron Mobility

Alava

Wang

Chen

et al. 2021

Adv Funct Materials

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The electron mobility in shallow GaAs/AlxGa1−xAs heterostructures is strongly suppressed by charge wafer surface, which arises from native surface oxide layers formed when the wafer is removed from the crystal growth system. Here an in situ epitaxial aluminum gate, grown as part of the wafer, is used to eliminate surface charge scattering. Transmission electron microscope characterization shows that the in situ epitaxial aluminum is crystalline, and the wafer surface is free of native oxide. The influence of Al thickness and the use of different semiconductor wetting layers at the semiconductor‐aluminum interface are examined and correlated with electron mobility. The electron mobility is found to strongly depend on aluminum thickness. For 8 nm thick aluminum, the electron mobility is also influenced by the wetting layer, with aluminum grown on GaAs producing higher mobility compared to AlAs or Al0.33Ga0.67As wetting layers. The suppression of surface charge scattering in these all‐epitaxial devices allows for high mobilities across a wide density range despite the shallow conduction channel (35 nm below the gate). These measurements also provide a uniquely sensitive method of determining the electrical quality of the semiconductor–metal interface, relevant to the formation of hybrid semiconductor–superconductor devices.

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“…The observed values of the local Zeeman field are explained by shifts of the QD positions of around 100 nm in the z direction, which is possible in this QQD device (see Supplementary Information ). The unexpected position-shift might be compensated by additional tuning of the gate voltages or removing inhomogeneous potentials by using undoped device structures 41 42 43 .…”

Section: Discussionmentioning

confidence: 99%

Single-electron Spin Resonance in a Quadruple Quantum Dot

Otsuka

Nakajima

Delbecq

et al. 2016

Sci Rep

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Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible.

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Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates

Abstract: This is a repository copy of Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates.

Cited by 10 publications

References 32 publications

Low-noise GaAs quantum dots for quantum photonics

Low-noise GaAs quantum dots for quantum photonics

Ultra‐Shallow All‐Epitaxial Aluminum Gate GaAs/Al_xGa_1−xAs Transistors with High Electron Mobility

Single-electron Spin Resonance in a Quadruple Quantum Dot

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Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates

Abstract: This is a repository copy of Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates.

Cited by 10 publications

References 32 publications

Low-noise GaAs quantum dots for quantum photonics

Low-noise GaAs quantum dots for quantum photonics

Ultra‐Shallow All‐Epitaxial Aluminum Gate GaAs/AlxGa1−xAs Transistors with High Electron Mobility

Single-electron Spin Resonance in a Quadruple Quantum Dot

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Product

Resources

About

Ultra‐Shallow All‐Epitaxial Aluminum Gate GaAs/Al_xGa_1−xAs Transistors with High Electron Mobility