Capacitance spectroscopy in quantum dots: Addition spectra and decrease of tunneling rates.

A theoretical study of single electron capacitance spectroscopy in quantum dots is presented. Exact diagonalizations and the unrestricted Hartree-Fock approximation have been used to shed light over some of the unresolved aspects. The addition spectra of up to 15 electrons is obtained and compared with the experiment. We show evidence for understanding the decrease of the single electron tunneling rates in terms of the behavior of the ! → 0 spectral weight function. Single electron capacitance spectroscopy (SECS) [1,2] has been a breakthrough in the experimental knowledge of the electronic structure of a quantum dot (QD). Ashoori and co-workers [1,2] have been able to determine the energies required to introduce electrons one by one, from 0 to 50, into a QD. The electrons tunnel into the QD by means of a vertical gate bias, and change the capacitance of the device. The measurement of that capacitance as a function of the Fermi energy EF in one electrode shows a discrete set of almost equally spaced peaks of different intensities. A peak appears whenever EF = � (N) = E0(N) − E0(N − 1), with E0(N) being the ground state (GS) energy of N electrons in the QD. In this way,