Geometric-disorder effects in lateral surface superlattices

The effects of static geometric disorder on the electronic structure of a model two-dimensional semiconductor superlattice are studied with the use of a coherent-potential description of off-diagonal disorder. The parameters in the model are chosen to represent as accurately as possible an array of short GaAs cylinders in a host matrix of ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$. The disorder scattering effects are found to be most pronounced near the band edges for disorder in cylinder size, and near the band center for disorder in cylinder spacing. The calculated electron damping rate is similar in magnitude to that obtained in previous calculations for phonon scattering, which indicated the persistence of negative differential mobility.