Single-electron effects in a point contact using side-gating in delta-doped layers

Side-gated point-contact structures in delta (δ)-doped layers have been used to form single-electron tunnel junctions with variable resistance. Clear Coulomb-blockade effects have been observed in the current-voltage characteristics. The measured characteristics are described in terms of a series of single-electron transistors formed by microsegments within the point contact. The effective tunnel capacitance and side-gate capacitance are estimated to be 10 and 1 aF, respectively, which are both one order of magnitude smaller than the reported capacitance of tunnel junctions made from Al or GaAs/AlGaAs heterostructures.