Growth of Al2O3 Nanowires on the Cu‐9 at.%Al(111) Single Crystal Surface

Abstract

Aluminum oxide structures were grown on Cu–9 at.%Al(111) single crystals. Usually alumina grows in the form of an epitaxial thin film. The process is based on Al atom segregation and subsequent oxidation of the Al topmost surface. Strong temperature dependence of the alumina growth mode was observed during the oxidation of a Cu–9 at.%Al single crystal. In this work we have reported for the first time the formation of alumina wire‐like nanostructures on the substrate surface during high‐temperature oxidation at low pressure. The nanowire growth was observed during substrate annealing at 1070 K while annealing at 910 K led to the formation of a flat and continuous thin alumina layer. Morphology, chemical composition, and structure characterization of the prepared nanostructures was done by means of scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy, and X‐ray diffraction. The experimental results point to the formation of Θ alumina phase nanowires due to surface segregation of Al atoms. Mechanism of alumina nanostructure formation is discussed. The experiment clearly showed that nanowire oxide structure growth can be obtained by a bottom‐up process with a mass transfer from the substrate to the assembled nanostructure.