Shell structure and electron-electron interaction in self-assembled InAs quantum dots

Abstract

Using far-infrared spectroscopy, we investigate the excitations of\nself-organized InAs quantum dots as a function of the electron number per dot,\n1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the\nwell-known two-mode spectrum is observed when the lowest s - states are filled,\nwe find a rich excitation spectrum for n=3, which reflects the importance of\nelectron-electron interaction in the present, strongly non-parabolic confining\npotential. From capacitance spectroscopy we find that the electronic shell\nstructure in our dots gives rise to a distinct pattern in the charging energies\nwhich strongly deviates from the monotonic behavior of the Coulomb blockade\nfound in mesoscopic or metallic structures.\n