Fabrication of ZnO microtube arrays via vapor phase growth

Single-crystalline ZnO microtube arrays were fabricated from commercial Zn powder on a Si substrate coated with a composite of fluororesin and SiO2 powder by making use of a simple one-step thermal evaporation process. The as-prepared ZnO samples were examined by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. It has been found that these ZnO microtubes are single-crystalline wurtzite structures, and grow along [0002] direction. The ZnO tubes with an outer diameter of ca. 1–3 μm have a length of several tens micrometers, of which the wall thickness ranges from 0.5 μm to 1.5 μm. The results have evidenced that the composite coating with a thickness of 0.1–1 mm is critical to the growth of the ZnO microtubes.