ABSTRACT
In this chapter, the theory and experiments for plasmon-based THz oscillators are reviewed. Two-dimensional (2D) plasmons in submicrometer-scaled transistors like field-effect transistors (FETs) and/or high-electron-mobility transistors (HEMTs) have attracted considerable attention due to their nature of promoting emission and detection of electromagnetic radiation in the THz range. First, the theory of hydrodynamics and instabilities of 2D plasmons are described. Second, experimental studies for massive 2D plasmons in InGaAs-based, GaAs-based, and GaN-based compound semiconductor heterostructures as well as massless 2D plasmons in graphene are described. In particular, graphene Dirac plasmons open a pathway towards the realization of intense THz laser transistors operating at room temperatures with a dry-cell battery. Third, future trends and technological subjects are addressed and their solutions are discussed.
