CHARGING EFFECTS IN QUANTUM DOTS

We have studied single electron charging effects in lateral quantum dots, defined by metal gates in the two dimensional electron gas of a GaAs/AlGaAs heterostructure. The charging effects cause periodic oscillations in the conductance versus gate voltage, where each period corresponds to a change of one electron in the dot. A study of the dependence of these Coulomb oscillations on the barrier conductances shows that charging effects become visible precisely when the barrier conductances become smaller than the quantized conductance value 2e2/h. The amplitude of the Coulomb oscillations increases gradually upon reducing the barrier conductances to a value much smaller than 2e2/h. We determine experimentally the total capacitance involved, and thereby the corresponding charging energy.