Absorption and photoluminescence spectroscopy on a single self-assembled   charge-tunable quantum dot
  We have performed detailed photoluminescence (PL) and absorption spectroscopy on the same single self-assembled quantum dot in a charge-tunable device. The transition from neutral to charged exciton in the PL occurs at a more negative voltage than the corresponding transition in absorption. We have developed a model of the Coulomb blockade to account for this observation. At large negative bias, the absorption broadens as a result of electron and hole tunneling. We observe resonant features in this regime whenever the quantum dot hole level is resonant with two-dimensional hole states located at the capping layer-blocking barrier interface in our structure. 
S. Seidl, M. Kroner, P. A. Dalgarno, A. H\"ogele, J. M. Smith, M.   Ediger, B. D. Gerardot, J. M. Garcia, P. M. Petroff, K. ...