Giant microwave photo-conductance of a tunnel point contact with a bridged gate

Levin, A. D.; Gusev, G. M.; Kvon, Z. D.; Bakarov, A. K.; Savostianova, N. A.; Mikhaǐlov, S. A.; Rodyakina, E. E.; Латышев, А. В.

doi:10.1063/1.4928733

Cited by 20 publications

(38 citation statements)

References 11 publications

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“…For more details on this mechanism see Refs. [9,10]. More detailed discussion of these effects is out of scope of the present paper focused on giant THz photoconductivity in the deep tunneling regime.…”

Section: Discussionmentioning

confidence: 98%

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Giant Terahertz Photoconductance of Quantum Point Contacts in the Tunneling Regime

et al. 2018

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We report on the observation of the giant photoconductance of a quantum point contact (QPC) in tunneling regime excited by terahertz radiation. Studied QPCs are formed in a GaAs/AlGaAs heterostructure with a high-electron-mobility two-dimensional electron gas. We demonstrate that irradiation of strongly negatively biased QPCs by laser radiation with frequency f = 0.69 THz and intensity 50 mW/cm 2 results in two orders of magnitude enhancement of the QPC conductance. The effect has a superlinear intensity dependence and increases with the dark conductivity decrease. It is also characterized by strong polarization and frequency dependencies. We demonstrate that all experimental findings can be well explained by the photon-mediated tunneling through the QPC. Corresponding calculations are in a good agreement with the experiment.

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Section: Discussionmentioning

confidence: 98%

“…Most recently it has been observed that excitation of a QPC with terahertz (THz) or microwave radiation results in an increase of the QPC conductance by about 50 times if it operates in the tunneling regime with G dark /G 0 ≈ 10 −3 , see Refs. [9,10]. These results were discussed in terms of photon-assisted tunneling.…”

Section: Introductionmentioning

confidence: 93%

Giant Terahertz Photoconductance of Quantum Point Contacts in the Tunneling Regime

et al. 2018

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“…Recently, in Ref. 10 , we have shown (at B = 0) that the Hall bars with the bridged-gate QPC demonstrate a two-three orders of magnitude higher sensitivity to the microwave irradiation than the structures with a traditional splitgate QPC. In the present work (B = 0, bridged-gate) we have found a much higher oscillation amplitude of the B-periodic oscillations (∆R/R ≃ 7) than in the ungated structures 5,8,9 or in structures with a split-gate QPC…”

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confidence: 99%

“…The microwave irradiation leads to the strong suppression of the resistance at zero magnetic field 10 . At B 0.7 T (corresponds to ω c ω) the resistance reveals the large B-periodic magnetoresistance oscillations.…”

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Giant microwave-induced B -periodic magnetoresistance oscillations in a two-dimensional electron gas with a bridged-gate tunnel point contact

et al. 2017

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We have studied the magnetoresistance of the quantum point contact fabricated on the high mobility two-dimensional electron gas (2DEG) exposed to microwave irradiation. The resistance reveals giant B-periodic oscillations with the relative amplitude ∆R/R of up to 700% resulting from the propagation and interference of the edge magnetoplasmons (EMPs) in the sample. This giant photoconductance is attributed to the considerably large local electron density modulation in the vicinity of the point contact. We have also analyzed the oscillation periods ∆B of the resistance oscillations and, comparing the data with the EMP theory, extracted the EMP interference length L. We have found that the length L substantially exceeds the distance between the contact leads but rather corresponds to the distance between metallic contact pads measured along the edge of the 2DEG. This resolves existing controversy in the literature and should help to properly design highly sensitive microwave and terahertz spectrometers based on the discussed effect. A number of interesting magnetotransport phenomena were discovered in recent years in a two-dimensional electron gas (2DEG) placed in a perpendicular magnetic field B and exposed to microwave (MW) irradiation. In low magnetic fields, corresponding to the condition ω c ω, the so called microwave-induced resistance oscillations (MIRO), with zero-resistance states, were observed 1-4 ; here ω c = eB/m * c and ω = 2πf are the cyclotron and microwave frequencies and m * is the electron effective mass. These oscillations of the diagonal resistance R are periodic in 1/B and are especially pronounced at low temperatures T ≃ 1 K in samples with a high electron mobility.In the opposite regime of higher magnetic fields, ω c ω, another type of magnetoresistance oscillations was discovered 5 . These oscillations are periodic in B and were explained by the excitation and interference of edge magnetoplasmons 6 (EMPs) in the sample. The incident microwave radiation excites oscillating (dipole) electric field at the boundaries between the 2DEG and metallic contacts. These dipole fields generate plasma waves -EMPs -propagating along the sample edge between the contacts on which the magnetoresistance R is measured. Due to the interference of EMPs, generated by different contacts, R oscillates as a function of the parameter qL, where q(ω, B) is the EMP wave-vector and L is the inter-contact distance 5 . In strong magnetic fields q(ω, B) is proportional to ωB/n s , where n s is the electron density 6,7 . This leads to the B-periodic oscillations with the period ∆B ∝ n s /ωL. This theoretically predicted dependence was confirmed by the experiments 5,8 . EMPs have a much smaller damping, as compared to the bulk magnetoplasmons, 6,7 and, in contrast to the MIRO-ZRS effect, the EMP-related oscillations do not require low temperatures and samples with the very high electron mobility: they were observed at least up to T ≃ 80 K 8 . These EMP properties make the considered phenomenon especially promising for the cre...

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Optically induced resonant tunneling of electrons in nanostructures

Boev,

Kovalev,

Kibis

2023

Sci Rep

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We developed the theory of elastic electron tunneling through a potential barrier driven by a strong high-frequency electromagnetic field. It is demonstrated that the driven barrier can be considered as a stationary two-barrier potential which contains the quasi-stationary electron states confined between these two barriers. When the energy of an incident electron coincides with the energy of the quasi-stationary state, the driven barrier becomes fully transparent for the electron (the resonant tunneling). The developed theory is applied to describe electron transport through a quantum point contact irradiated by an electromagnetic wave.

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Giant microwave photo-conductance of a tunnel point contact with a bridged gate

Abstract: Articles you may be interested inSplit-gate quantum point contacts with tunable channel length

Cited by 20 publications

References 11 publications

Giant Terahertz Photoconductance of Quantum Point Contacts in the Tunneling Regime

Giant Terahertz Photoconductance of Quantum Point Contacts in the Tunneling Regime

Giant microwave-induced B -periodic magnetoresistance oscillations in a two-dimensional electron gas with a bridged-gate tunnel point contact

Optically induced resonant tunneling of electrons in nanostructures

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