Theoretical Studies of Light Scattering from Solids, Films and Surfaces

摘要

We've investigated the conditions necessary to achieve strong plasmon instability at low temperature leading to emission in the terahertz regime for quantum wells. The surface response function was calculated for a bilayer two-dimensional electron gas (2DEG) system under a metal grating placed on the surface and which modulates the electron density. The 2DEG layers are coupled to surface plasmons arising from excitations of free carriers in the bulk region between the layers. A current is passed through one of multiple layers and is characterized by a drift velocity. We have also been investigating a system with relativistic like dispersion, e.g. graphene. The plasma excitations change considerably when the Fermi energy is at or close to the Dirac point. Several properties of graphene and graphene nanoribbons, e.g. the ballistic conductances optical conductivity, tunneling, effect of magnetic field on the plasmon excitations, and possible Bose-Einstein condensation in a double layer configuration were the subjects of our published works.