Fabrication of a single-electron transistor by current-controlled local oxidation of a two-dimensional electron system

The surface layers of a GaAs/AlGaAs heterostructure are locally oxidized using an atomic force microscope. The local anodic oxidation depletes the underlying two-dimensional electron gas leading to the formation of tunneling barriers. The height of the barriers is determined by measuring the thermally activated current. By varying the oxidation current, the barrier heights can be tuned between a few meV and more than 100 meV. Using these barriers as tunneling elements, a side gated single-electron transistor is fabricated.