Disorder and interaction-induced pairing in the addition spectra of quantum dots

We have numerically investigated the electron addition spectra in quantum d ots containing a small number (N less than or equal to 10) of interacting e lectrons, in the presence of strong disorder. For a short-range Coulomb rep ulsion. we find regimes in which two successive electrons enter the dot seq uentially but almost at the same value of the chemical potential. in the st rongly correlated regime these close additions, or pairings, are associated with electrons tunneling into distinct electron puddles within the dot. We discuss the tunneling rates at pairing and argue that the results an relat ed to a recently observed phenomenon known as bunching.