Charged excitons in self-assembled semiconductor quantum dots

Interband excitations of an ensemble of InAs self-assembled quantum dots have been directly observed in transmission experiments. The dots are embedded in a field-effect structure allowing us to load the dots electrically. We establish an exact correspondence between Coulomb blockade in the device's vertical transport properties and Pauli blocking in the transmission spectra. We observe substantial shifts, up to 20 meV, in the energies of the higher excitations on occupation of the electron ground state. We argue that this is a consequence of an exciton-electron interaction.