Electronic properties of nanostructures defined in Ga[Al]As heterostructures by local oxidation

Tunable nanostructures can be patterned in Ga[Al]As heterostructures with an atomic force microscope (AFM). Oxidizing the GaAs cap layer locally by applying a voltage to the AFM tip leads to depletion of the electron gas underneath the oxide. Here, we describe this type of AFM lithography as a tool to fabricate tunable nanostructures and characterize the electronic properties of the resulting confinement. As an example for the versatility of this technique, we present conductance measurements on a quantum wire as a function of its position. Conductance fluctuations in real space with a characteristic period of 2 nm are observed and interpreted in terms of individual peaks in the potential landscape the wire hits as it moves through the host crystal. (C) 2001 Elsevier Science B.V. All rights reserved.