Terahertz Radiation from the Dyakonov-Shur Instability of Hydrodynamic Electrons in a Corbino Geometry

TL;DR

This paper investigates how the Dyakonov-Shur instability in hydrodynamic electrons within a Corbino disk geometry can generate terahertz radiation, showing enhanced instability characteristics and potential for practical terahertz sources.

Contribution

It demonstrates that the Corbino geometry significantly enhances the Dyakonov-Shur instability, lowering the critical drift velocity and increasing power output, with implications for terahertz radiation sources.

Findings

Enhanced instability in Corbino geometry

Lower critical drift velocity for instability

Higher power generation potential

Abstract

Hydrodynamic electrons flowing through a two-dimensional channel are predicted to undergo a plasma instability above a critical drift velocity. This Dyakonov-Shur (DS) instability terminates as a coherent nonlinear oscillator which shows promise as a source of radiation that could fill the so-called TeraHertz gap. In this work, we study radial flow in a Corbino disk, and demonstrate how the DS instability is substantially enhanced in this geometry, both in terms of a lower critical drift velocity and a higher generated power. Interestingly, hydrodynamic electron flows were recently reported in a graphene sample of this geometry, and our results are therefore directly relevant to current efforts to detect this experimentally elusive phenomenon. The analysis is based on a hydrodynamic approach and features both linearized calculations as well as full numerical simulations of the Navier-Stokes equation.