Room-Temperature Plasmon-Resonant Terahertz Graphene Photodetectors

Dr. José M. Caridad1,2, Mr. Óscar Castelló1,2, Ms. Sofía M. Lopez Baptista1, Dr. Takashi Taniguchi3, Dr. Kenji Watanabe4, Prof. Hartmut G. Roskos5, Dr. Juan A. Delgado Notario1
1Department of Applied Physics, University of Salamanca, Salamanca, Spain. 2Unidad de Excelencia en Luz y Materia Estructurada (LUMES), Universidad de Salamanca, Salamanca, Spain. 3Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan. 4Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan. 5Physikalisches Institut, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany


Frequency-selective or even frequency-tunable Terahertz (THz) photodevices are critical components for many technological applications that require nanoscale manipulation, control and confinement of light. Within this context, gate-tunable phototransistors based on plasmonic resonances are often regarded as the most promising devices for frequency-selective detection of THz fields.  The exploitation of constructive interference of plasma waves in such detectors not only promises frequency selectivity, but also a pronounced sensitivity enhancement at the target frequencies. However, clear signatures of plasmon-assisted resonances in THz detectors have been only revealed at cryogenic temperatures and so far, have remained unobserved at application-relevant room-temperature conditions. Here, we demonstrate the sought-after room-temperature resonant photodetection of THz radiation in short-channel gated photodetectors made from high-quality single-layer graphene. The survival of this intriguing resonant regime at room-temperature ultimately relies on the weak intrinsic electron-phonon scattering in graphene, which avoids the damping of the plasma oscillations.