Elastic and inelastic scattering in quantum dots in the Coulomb-blockade regime

Starting from a rate-equation model proposed by Beenakker, we calculate current-voltage characteristics for symmetric and asymmetric vertical quantum dots. We include up to 26 electrons and show how single-electron charge interaction, inelastic scattering, and nonadiabatic subband mixing can enhance the valley current significantly by opening new conduction channels. Subband mixing is the dominant mechanism increasing the valley current in both symmetric and asymmetric quantum dots. Single-electron charging is important in asymmetric structures but relatively weak in symmetric structures. Effects of inelastic scattering within the quantum dot are dramatic for asymmetric structures, but negligible in symmetric structures.