Excitation, detection, and electrostatic manipulation of terahertz-frequency range plasmons in a two-dimensional electron system

TL;DR

This paper presents a novel terahertz plasmonic circuit integrating photoconductive material with a 2D electron system, enabling excitation, detection, and electrostatic control of plasmons up to 400 GHz for studying nanoscale transport dynamics.

Contribution

It introduces a monolithic planar terahertz plasmonic circuit with tunable resonances, allowing in-plane excitation and electrostatic manipulation of plasmons in 2D electron systems.

Findings

Plasmons excited up to ~400 GHz in the device.

Voltage modulation tunes plasmonic cavity resonances.

Direct access to picosecond dynamics of confined transport.

Abstract

Terahertz time domain spectroscopy employing free-space radiation has frequently been used to probe the elementary excitations of low-dimensional systems. The diffraction limit blocks its use for the in-plane study of individual laterally defined nanostructures, however. Here, we demonstrate a planar terahertz-frequency plasmonic circuit in which photoconductive material is monolithically integrated with a two-dimensional electron system. Plasmons with a broad spectral range (up to ~400 GHz) are excited by injecting picosecond-duration pulses, generated and detected by a photoconductive semiconductor, into a high mobility two-dimensional electron system. Using voltage modulation of a Schottky gate overlying the two-dimensional electron system, we form a tuneable plasmonic cavity, and observe electrostatic manipulation of the plasmon resonances. Our technique offers a direct route to access the picosecond dynamics of confined transport in a broad range of lateral nanostructures.