posted on 2024-01-02, 16:35authored byJosé
M. Caridad, Óscar Castelló, Sofía M. López Baptista, Takashi Taniguchi, Kenji Watanabe, Hartmut G. Roskos, Juan A. Delgado-Notario
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 the frequency-selective
detection of THz radiation. The exploitation of constructive interference
of plasma waves in such detectors promises not only frequency selectivity
but also a pronounced sensitivity enhancement at target frequencies.
However, clear signatures of plasmon-assisted resonances in THz detectors
have been revealed only at cryogenic temperatures so far and remain
unobserved at application-relevant room-temperature conditions. In
this work, we demonstrate the sought-after room-temperature resonant
detection 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 monolayer graphene,
which avoids the damping of the plasma oscillations present in the
device channel.