Treatment of ZnO nanowires on Si(111)

We investigated vapour-phase-epitaxy grown ZnO NWs on a Si substrate by SEM. SEM investigations show that there are single NWs and ensembles of NWs, among which we found straight and bend, perfect (with regular facets and smooth surfaces) and non-perfect (with irregular facets, non smooth surfaces, variable widths, damaged and particle) NWs, as well as NWs with clean surfaces, and surfaces with dark spots and features. After FIB polishing, we found that every NW has a clean homogeneous surface, which allows us to conclude that all its dark spots and surface features are really just surface features. The FIB milling gives information regarding the deeper interior of the NWs, i.e. buried structures within them, and whether or not those structures are propagating within them. But also here we found that there are no buried structures inside the NWs and the dark spots and features are not propagating within them, which lead to the result that NWs are totally homogeneous. The hexagonal facets of the NWs were observed on SEM images, which emphasize their good crystalline quality. The sizes of NWs were determined: the length is about 2–24 μm, and the width and height are about 200–500 nm.