Singularity-Enhanced Terahertz Detection in High-Mobility Field-Effect Transistors

Abstract

Detectors of high-frequency radiation based on high-electron-mobility transistors benefit from low noise, room-temperature operation, and the possibility to perform radiation spectroscopy using gate-tunable plasmon resonance. Despite successful proof-of-concept demonstrations, the responsivity of transistor-based detectors of terahertz radiation, at present, remains fairly poor. To resolve this problem, we propose a class of devices supporting singular plasmon modes, i.e., modes with strong electric fields near keen electrodes. A large plasmon-enhanced electric field results in amplified nonlinearities, and thus efficient ac-to-dc conversion. We analyse subterahertz detectors based on a two-dimensional electron system in the Corbino geometry as a prototypical and exactly solvable model, and show that the responsivity scales as $1/{r}_{0}^{2}$ with the radius of the inner contact ${r}_{0}$. This enables responsivities exceeding 10 kV/W at subterahertz frequencies for nanometer-scale contacts readily accessible by modern nanofabrication techniques.