Nanoscale oxidation of InAs and its device applications

Atomic force microscope (AFM) oxidation is applied for a nanostructure fabrication of a thin InAs layer and the current-voltage characteristics of the oxidized InAs region is studied. The nonlinear current-voltage characteristics show that this AFM oxidation renders the InAs layer into a highly resistive one that can be used either as a gate insulator or as a tunneling barrier. A single-electron-transistor (SET) structure with the island size of 80 nm/spl times/80 nm and in-plane-gate electrodes on each side of the narrow channel was fabricated by this AFM oxidation process in order to demonstrate the feasibility of the technique for a nanostructure device fabrication. The device characteristics measured at 4.2 K show field-effect-transistor characteristics indicating the successful formation of the gate insulator and SET operations with the oscillation period of 140 mV. The results demonstrate that this AFM oxidation process provides a novel fabrication capability for InAs-based nanostructure devices. In addition, AFM oxidation characteristics were studied using ac tip voltages. It was found that a further reduction in the fabrication size by 10-20 nm is obtained for ac voltages due to the improvement in the aspect ratio of AFM oxidation.