Coulomb electron drag mechanism of terahertz plasma instability in n+-i-n-n+ graphene FETs with ballistic injection

TL;DR

This paper predicts terahertz plasma oscillations in graphene FETs caused by Coulomb drag, which could enable room-temperature THz radiation sources with realistic device parameters.

Contribution

It introduces a novel mechanism for terahertz plasma instability in graphene FETs based on Coulomb drag of ballistic electrons, with conditions for self-excitation.

Findings

Self-excitation of THz oscillations predicted in graphene FETs.

Plasma frequency depends on the Fermi energy of electrons.

Conditions achievable at room temperature with realistic device parameters.

Abstract

We predict the self-excitation of terahertz (THz) oscillations due to the plasma instability in the lateral n+-i-n-n+$ graphene field-effect transistors (G-FET). The instability is associated with the Coulomb drag of the quasi-equilibrium electrons in the gated channel by the injected ballistic electrons resulting in a positive feedback between the amplified dragged electrons current and the injected current. The plasma excitations arise when the drag effect is sufficiently strong. The drag efficiency and the plasma frequency are determined by the quasi-equilibrium electrons Fermi energy (i.e., by their density). The conditions of the terahertz plasma oscillation self-excitation can be realized in the G-FETs with realistic structural parameters at room temperature enabling the potential G-FET-based radiation sources for the THz applications.