A discrete drift-diffusion model is derived from a microscopic sequential tunneling model of charge transport in weakly-coupled superlattices provided temperatures are low or high enough. Realistic transport coefficients and contact current-field characteristic curves are calculated from microscopic expressions, knowing the design parameters of the superlattice. Boundary conditions clarify when possible self-sustained oscillations of the current are due to monopole or dipole recycling.

• Received 29 September 1999

DOI:https://doi.org/10.1103/PhysRevB.62.2786