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An in-plane photoelectric effect in two-dimensional electron systems for terahertz detection

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Michailow, Wladislaw  ORCID logo
Kindness, Stephen J  ORCID logo
Wallis, Robert 


Many mid and far infrared semiconductor photodetectors rely on a photonic response, when the photon energy is large enough to excite and extract electrons due to optical transitions. Towards the terahertz range with photon energies of a few meV, classical mechanisms are employed instead. This is the case in two-dimensional electron systems, where terahertz detection is dominated by plasmonic mixing and by scattering-based thermal phenomena. Here, we report on the observation of a quantum, collision-free phenomenon which yields a giant photoresponse at terahertz frequencies (1.9 THz), more than ten-fold as large as expected from plasmonic mixing. We artificially create an electrically tunable potential step within a degenerate two-dimensional electron gas. When exposed to terahertz radiation, electrons absorb photons and generate a large photocurrent under zero source-drain bias. The observed phenomenon, which we call the "in-plane photoelectric effect", provides an opportunity for efficient direct detection across the entire terahertz range.



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Science Advances

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American Association for the Advancement of Science
Engineering and Physical Sciences Research Council (EP/P021859/1)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (881603)
George and Lilian Schiff Studentship, Schiff Foundation, University of Cambridge Honorary Vice-Chancellor’s Award, Cambridge Trust, University of Cambridge
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