Giant terahertz photoconductance of tunneling point contacts

Abstract

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.

arXiv comment8 pages, 8 figures

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• Quantum Point Contacts
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Cited by in corpus (4)

• Terahertz photoconductivity in bilayer graphene transistors: evidence for tunneling at gate-induced junctions
• Optically induced resonant tunneling of electrons in nanostructures
• Highly Superlinear Giant Terahertz Photoconductance in GaAs Quantum Point Contacts in the Deep Tunneling Regime
• Spectral maximum in the terahertz photoconductance of a quantum point contact