Growth of ZnO and ZnMgO nanowires by Au-catalysed molecular-beam epitaxy

We have studied oxygen-plasma assisted molecular-beam epitaxy growth of ZnMgO nanostructures catalysed by gold. The growth was carried out at temperatures ranging from 350 to 900 degrees C. Au droplets were prepared by annealing a thermally evaporated Au thin film, or by deposition of Au colloidal particles, or by electron-beam lithography with a subsequent Au lift-off deposition process. The resulting nanowires grow at temperatures in the range 700-850 degrees C with diameter 40-100 nm and with length up to 4 m. In order to increase nanowire density and reduce tapering, two-step growth with a ZnO low-temperature buffer-layer was successfully implemented. To study Mg incorporation into ZnO nanowires, Zn1-xMgxO nanowires were grown with normalized Mg flux up to 11%. High resolution microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction reveal that Mg-doped nanowires grow in single phase with Mg content up to 7.5%. [GRAPHICS] Gold catalysed ZnO nanowires grown by molecular-beam epitaxy. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim