Superlattice electrodynamics as a source of Terahertz radiation

Charge-carriers propagating in superlattices exhibit the related phenomena known as negative differential conductivity and Bloch oscillation. This behaviour may be utilised for the generation of tunable electromagnetic radiation. In this work, the dependence of the drift velocity and displacement of charge-carriers on external, applied electric fields is investigated. The theory is extended to incorporate a different miniband structure, with the aim of modelling a superlattice made from graphene. I predict that, for a chosen set of electric field parameters, a semiconductor superlattice will emit radiation in the terahertz range. I create an original mathematical framework within which to calculate the charge-carrier behaviour in a triangular miniband structure, while incorporating an arbitrary variable to account for the effects of corrugation or disorder, and predict the appearance of conductivity multistability. This may be of interest to further work done on the use of graphene for superlattice device construction.