AlGaAs/GaAs single electron transistor fabricated without modulation doping

See, A. M.; Klochan, O.; Hamilton, A. R.; Micolich, A. P.; Aagesen, Martin; Lindelöf, P. E.

doi:10.1063/1.3358388

Cited by 27 publications

(37 citation statements)

References 21 publications

(23 reference statements)

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“…34 No RTS event could be observed in the electron quantum dot fabricated on the SISFET of Ref. [33]. Figure 2 shows Coulomb blockade (CB) oscillations in the weak coupling regime from one of three quantums dot fabricated on wafer V627 (the other two devices have similar characteristics as those shown here).…”

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confidence: 80%

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Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas

Mak

Sfigakis

Gupta

et al. 2013

Applied Physics Letters

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We report quantum dots fabricated on very shallow 2-dimensional electron gases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostuctures grown by molecular beam epitaxy. Due to the absence of dopants, an improvement of more than one order of magnitude in mobility (at 2×10 11 cm −2 ) with respect to doped heterostructures with similar depths is observed. These undoped wafers can easily be gated with surface metallic gates patterned by e-beam lithography, as demonstrated here from single-level transport through a quantum dot showing large charging energies (up to 1.75 meV) and excited state energies (up to 0.5 meV).Electrostatically-defined quantum dots fabricated on high-mobility GaAs/AlGaAs heterostructure have been − and continue to be − invaluable in many fundamental investigations, e.g. Kondo physics and spin-based solid-state qubits. Unfortunately, the characteristics of these devices are extremely sensitive to seemingly random charge fluctuations in their local electrostatic potential, commonly known as Random Telegraph Signal (RTS) noise, or charge noise. Although one can perform a biased cooling 1,2 or a thermal cure 3 to attempt to drastically reduce the levels of charge noise on a given device, results from both techniques vary from device to device.Quantum dots fabricated in shallow two-dimensional electron gases (2DEGs) have two advantages over their deeper cousins. First, finer features can be transferred from the surface metallic gates to the 2DEG. Second, the energy scales of the dot levels tends to be larger, which enable operation at higher temperatures. However, shallow 2DEG depths (as little as 20 nm below the surface) come at the expense of mobility.4-14 Furthermore, the dopant layer may partially screen surface gates (through hopping conduction) and/or facilitate gate leakage, rendering many such wafers ungateable by surface metallic gates. The ungateability of some doped wafers is not only restricted to shallow 2DEGs, but also can occur in high-mobility doped wafers. 15-17The limitations described above can be circumvented or mitigated by using undoped heterostructures in different field-effect transistor (FET) geometries such as the SISFET 18-22 (semiconductor-insulator-semiconductor), the MISFET 23-25 (metal-insulator-semiconductor), or the HIGFET 26 (heterostructure-insulator-gate). Since there are no intentional dopants, the 2DEG can be brought much closer to the surface without sacrificing mobility. Furthermore, undoped quantum dots would not suffer from one possible source of charge noise: electrons hopping between dopant sites in AlGaAs. In doped wafers, intentional dopants typically outnumber unintentional dopants 10,000 to 1 (depending on mobility). Finally, undoped quantum dots may also interact with fewer undesirable impurities in the vicinity and are far more reproducible upon thermal cycling than their doped counterparts.27 In this Letter, we compare ultra-shallow undoped and doped GaAs/AlGaAs 2DEGs, and demonstrate gated quantum dots on ultra-shallow undoped heter...

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confidence: 80%

“…The (weak coupling regime) charging energy in our MISFET (U = 1.25 meV) is larger than that (U = 0.5 meV) of the quantum dot on the SISFET from Ref. [33]. The single-particle energy level spacing (∆E) FIG.…”

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confidence: 99%

Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas

Mak

Sfigakis

Gupta

et al. 2013

Applied Physics Letters

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“…The strong V g dependence of the noise, in turn, allowed the reduction of the charge noise by employing bias cooling 14 or an additional global top gate, 15 both of which shift the operation point to a less negative voltage. In an attempt to eliminate the charge noise associated with doping, single-electron transistors based on undoped structures have been fabricated; 19 however, the anticipated noise reduction has not yet been demonstrated.…”

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confidence: 99%

Intrinsic and extrinsic origins of low-frequency noise in GaAs/AlGaAs Schottky-gated nanostructures

Hitachi

Ôta

Muraki

2013

Applied Physics Letters

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We study low-frequency noise in current passing through quantum point contacts fabricated from several GaAs/AlGaAs heterostructures with different layer structures and fabrication processes. In contrast to previous reports, there is no gate-dependent random telegraph noise (RTN) originating from tunneling through a Schottky barrier in devices fabricated using the standard low-damage process. Gate-dependent RTN appears only in devices fabricated with a high-damage process that induces charge trap sites. We show that the insertion of AlAs/GaAs superlattices in the AlGaAs barrier helps to suppress trap formation. Our results enable the fabrication of damage-resistant and thus low-noise devices.

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“…[22][23][24] Undoped GaAs/AlGaAs heterostructures have better interfacial properties than Si/SiO 2 19 and have no valley interference as observed for Si/SiGe. 24 By employing undoped GaAs/ AlGaAs systems, researchers have successfully developed single quantum dots with electron carriers 25,26 and double quantum dots (DQDs) with hole carriers. 27 Double quantum dots with electron carriers are expected to be useful for further investigation of the coherence controllability and decoherence noise level of single electron-based quantum devices in undoped GaAs/AlGaAs.…”

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Fabrication and characterization of an undoped GaAs/AlGaAs quantum dot device

Cao

Xiao

et al. 2014

Journal of Applied Physics

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We demonstrate the development of a double quantum dot with an integrated charge sensor fabricated in undoped GaAs/AlGaAs heterostructures using a double top-gated design. Based on the evaluation of the integrated charge sensor, the double quantum dot can be tuned to a few-electron region. Additionally, the inter-dot coupling of the double quantum dot can be tuned to a large extent according to the voltage on the middle gate.The quantum dot is shown to be tunable from a single dot to a well-isolated double dot. To assess the stability of such design, the potential fluctuation induced by 1/f noise was measured. Based on the findings herein, the quantum dot design developed in the undoped GaAs/AlGaAs semiconductor shows potential for the future exploitation of nano-devices.Electrically gate-defined semiconductor quantum dots fabricated on modulation doped GaAs/AlGaAs heterostructures are widely used to explore electron transport behaviors and to realize solid state qubits. [1][2][3][4][5][6][7][8] They have attracted much interest because of their remarkable coherence controllability by tuning parameters in a two-level system with electrical gates. 9-13 However, it is believed that doped heterostructures may suffer from significant charge noise owing to surface gate leakage and charge fluctuation in the doping layer, [14][15][16][17][18] thereby resulting in an important decoherence source for solid state qubits. 15,16 Removal of the ionized doping layer, leading to an undoped semiconductor, may provide a good platform for implementing various quantum devices. Because an additional top gate is used to accumulate charge carriers under the conventional depletion gates, the double-gate architecture is usually adopted in undoped semiconductor devices. Recently, there have been a series of reports on double-gated quantum dots in undoped Si/SiO2 [19][20][21] and Si/SiGe materials. [22][23][24]

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AlGaAs/GaAs single electron transistor fabricated without modulation doping

Cited by 27 publications

References 21 publications

Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas

Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas

Intrinsic and extrinsic origins of low-frequency noise in GaAs/AlGaAs Schottky-gated nanostructures

Fabrication and characterization of an undoped GaAs/AlGaAs quantum dot device

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