THz wave generation in cylindrical heterostructure nanowire

In this paper, we consider THz plasma radiation in ungated cylindrical heterostructure nanowire (NW) or carbon nanotube (CNT) via perturbation approach, considering the effect of viscosity, momentum relaxation time and drift velocity as sufficiently small quantities. The scalar potential, channel charge and current are determined by solving Euler, continuity and Poisson equations in cylindrical coordinates with appropriate boundary conditions using Dyakonov-Shur plasma theory. We obtain a general dispersion relation, plasma frequency, increment and the radiated power. It is shown that in the limit of small radius, the plasma frequency behaves logarithmically while in the limit of large radius, the plasma frequency approaches to the plasma frequency of flat two-dimensional electron gas (flat-2DEG). We show that as in the flat-2DEG, drift velocity increases instability of plasma waves while viscosity and momentum relaxation time decreases the instability.