Shell filling in non-linear magneto-tunneling spectroscopy of vertical   quantum dots
  We report on non-linear magneto-tunneling experiments carried out in single GaAs vertical quantum dots.   We show that conduction at low voltage bias can be a spectroscopic tool for both the ground state and first excited states of few electrons on the dot. Increasing voltage a large resonant peak is observed and attributed to tunneling across the quasi-continuum of higher excited states. 
B. Jouault, G. Faini, A. Angelucci, M. Di Stasio, G. Santoro, A.   Tagliacozzo, F. Laruelle, R. Werner, A. Forchel