Electrical damage induced by ion beam etching of GaAs

Abstract

We have examined the electrical damage induced in GaAs by ion milling and ion beam assisted etching, relevant to the fabrication of small conducting structures. The depth of the damage was measured by Schottky barrier measurements with in situ deposited gold contacts and by resistance and mobility measurements of etched two-dimensional electron gas structures. The effect of exposed etched sidewalls on the conductivity of narrow wires was examined for GaAs/AlGaAs structures. We find that it is possible to create wires narrower than surface depletion lengths by defining the structures through ion beam induced damage without exposing the sidewalls. In particular, narrow conducting wires can be defined solely by etching the thin-undoped-GaAs cap layer atop the modulation doped material.