Plasma waves in two-dimensional electron-hole system in gated graphene heterostructures

TLDR

The study assumes conical, zero‑effective‑mass energy spectra for two‑dimensional electrons and holes. The paper theoretically investigates plasma waves in a gate‑controlled graphene heterostructure containing a two‑dimensional electron‑hole system. The authors calculate the plasma‑wave spectrum by modeling spatio‑temporal variations of electron and hole densities and the self‑consistent electric potential. They find that long plasma waves exhibit a linear, sound‑like dispersion with a velocity set by gate thickness, voltage, and temperature, which can exceed that in conventional semiconductor heterostructures and enable voltage‑tunable terahertz devices.

Abstract

Plasma waves in the two-dimensional electron-hole system in a graphene-based heterostructure controlled by a highly conducting gate are studied theoretically. The energy spectra of two-dimensional electrons and holes are assumed to be conical (neutrinolike), i.e., corresponding to their zero effective masses. Using the developed model, we calculate the spectrum of plasma waves (spatio-temporal variations of the electron and hole densities and the self-consistent electric potential). We find that the sufficiently long plasma waves exhibit a linear (soundlike) dispersion, with the wave velocity determined by the gate layer thickness, the gate voltage, and the temperature. The plasma wave velocity in graphene heterostructures can significantly exceed the plasma wave velocity in the commonly employed semiconductor gated heterostructures. The gated graphene heterostructures can be used in different voltage tunable terahertz devices which utilize the plasma waves.