Landau-level terahertz emission from electrically biased graphene
Fumiyuki Inamura,
Gen Ueda,
Sunmi Kim,
Mikhail Patrashin,
Iwao Hosako,
Susumu Komiyama,
Kenji Ikushima
Affiliations
Fumiyuki Inamura
Faculty of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
Gen Ueda
Faculty of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
Sunmi Kim
National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
Mikhail Patrashin
School of Physics, Chemistry and Earth Sciences, Faculty of Sciences, Engineering and Technology, The University of Adelaide, Adelaide, South Australia 5005, Australia
Iwao Hosako
National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
Susumu Komiyama
Department of Basic Science, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
Kenji Ikushima
Faculty of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
Terahertz (THz) emission from electrically biased graphene is studied under high magnetic fields. A quantum well (QW)-based charge-sensitive infrared phototransistor (CSIP) is used to detect weak THz emission from a graphene Hall bar. THz emission is clearly observed at around 5 T when the Hall voltage exceeds the corresponding Landau-level (LL) energy spacing between the zero-energy (N = 0) and first excited (N = +1 or N = −1) LLs, suggesting that the emission occurs primarily at the carrier entry and exit corners of the current contacts in the Hall bar. We also investigate the emission spectra through measurements of the QW spectrum of the CSIP. The emission spectra are well explained by the N = +1 → 0 (or N = −1 → 0) inter-LL radiative transition in monolayer graphene. The linewidth of the emission spectra is estimated to be on the order of 10 meV, even though no explicit LL splitting is observed in the magnetotransport at 5 T.
