Electrical tunability of terahertz amplification in a periodic plasmon graphene structure with charge-carrier injection

The dependence of the plasmon terahertz resonant frequency in the generation mode on the quasi-Fermi energy in the active (ungated) region of graphene with an inverse charge carrier population and on the Fermi energy in the gated $p$- and $n$-type regions in a periodic $p$–$i$–$n$ structure based on graphene with injection pumping is theoretically investigated. It is shown that electrically frequency-tunable nanoscale plasmon graphene amplifiers and generators operating in a broad terahertz frequency range at room temperature can be designed.