The growth mechanism of vertically aligned ZnO nanowire arrays on non-epitaxial Si(100) substrates

Abstract

In this report, we have investigated the Au-assisted growth of ZnO nanowires at a low temperature (550 oC) using low melting point Zn metal as a source. We supplied various Ar gas flow rate to carry Zn vapor onto Au catalysts coated Si(100) substrates to grow ZnO nanowires. When a high Ar gas flow rate was supplied, a large amount Zn vapor was carried onto the substrate and reacted with O2 to form a ZnO buffer layer covering the surface of the Au catalysts. This ZnO buffer layer has a highly c-axis pREFerential orientation, which helps form vertically aligned ZnO nanowire arrays. In this condition, no Au catalysts appeared on the tips of the ZnO nanowires.When low Ar gas flow rate was supplied, Zn vapor is too low to form ZnO buffer layer on the surface of Au catalysts. From TEM analysis, we can observe that Au catalysts remain solid during growth. The detail growth mechanism of ZnO nanowires with various carrier flow rates was studied by field-emission electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).