Electron microscopy of copper oxidation

Abstract

Single-crystal copper specimens of various orientations have been cleaned, oxidized and examined by reflection high-energy electron diffraction in a XJHV chamber and then transferred, under vacuum, to a transmission electron microscope where the shape and orientation of the individual oxide islands could be examined. On all surfaces the islands had a regular appearance with three or four interfaces, the oxide interfacial planes were always {110} and fitted close to either {110} or {114} copper planes. Allowing for tilts of a few degrees, the same epitaxy was observed on all copper faces, the amount of tilt depending on the original surface orientation. Surface steps were shown to be a very important factor in the initial nucleation, influencing the adsorption of oxygen, the siting of the nuclei and the oxide orientation.