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 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. The possibility of creating novel electronic devices on the basis of graphene heterostructures and has caused a surge of experimental and theoretical publications. The plasma waves in graphene-based heterostructures, in which the 2D electron or hole system can serve as a resonant cavity or as a voltage-controlled waveguide, can be used in different devices operating in the terahertz range of frequencies. The plasma frequency versus wavenumber dependences are close to linear dependences at small wavenumbers. The electron and hole sheet densities in graphene heterostructures with the conducting gate can be effectively varied by the gate voltage.
