Coupled lateral and vertical electron dynamics in semiconductor superlattices

We develop a theoretical description for a weakly coupled semiconductor superlattice which allows for laterally inhomogeneous charge distributions within one well. We use this model to study the dynamical stability of mixed initial states in which different regions of the superlattice are associated with the different branches in the multistable current-voltage characteristic. It is found that mixed states can indeed exist for a long time; their stability, however, depends very sensitively on the applied external voltage.