Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (0001) GaN/sapphire substrate using Vapor-Liquid-Solid (VLS) technique were studied using electron microscopy and X-ray diffraction. The results revealed presence of both horizontal (crawling-like) and vertical nanowires having similar orientation relationship to the substrate (00.1)ZnO||(00.1)GaN, [11.0]GaN. The crawling-like growth precedes the vertical growth, and the coalescence and overgrowth of the crawling nanowires produce a highly defective layer which separates the substrate and vertical nanorods. Transmission electron microscopy revealed a high density of planar defects in this interfacial layer. Significant density of stacking faults residing on the (0001) planes was also observed in the shorter vertical nanorods. X-ray diffraction revealed that the crawling nanowires endure residual compressive strain, whereas the vertical nanorods grow strain-free.
Citation: Applied Physics/ Letters
Pub Type: Journals
electron microscopy, GaN, growth, nanowire, ZnZ