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

2022; American Association for the Advancement of Science; Volume: 8; Issue: 15 Linguagem: Inglês

10.1126/sciadv.abi8398

2375-2548

Wladislaw Michailow, Peter Spencer, Nikita W. Almond, Stephen J. Kindness, R. Wallis, Thomas A. Mitchell, Riccardo Degl’Innocenti, S. A. Mikhaǐlov, Harvey E. Beere, D. A. Ritchie,

Semiconductor Quantum Structures and Devices

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. Toward the terahertz range with photon energies of a few milli–electron volts, classical mechanisms are used 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 that yields a giant photoresponse at terahertz frequencies (1.9 THz), more than 10-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.