Nanolithography on semiconductor heterostructures by local oxidation with an atomic force microscope

Abstract

We demonstrate that tunable nanostructures in Ga[Al]As heterostructures can be patterned with an atomic force microscope (AFM). By application of suitable voltages to the conductive tip of the AFM, the sample can be oxidized in close vicinity of the tip. Both the semiconductor surface itself as well as gate electrodes on top of it can be modified this way. While sufficiently thin metallic electrode films can be cut into electronically isolated parts by oxidizing them, an oxidation of the GaAs cap layer of a shallow heterostructure leads to depletion of the electron gas underneath the oxide. Here, we discuss AFM lithography as a tool to fabricate tunable semiconductor nanostructures.