Growth and characterization of vertically aligned ZnO microtubes on silicon substrate

Vertically aligned Zinc oxide (ZnO) microtubes with a hexagonal hollow texture were synthesized by metal organic chemical vapor deposition technique on silicon substrates without any catalyst. Structural and optical characterizations of the as-grown microstructures have been carried out at room temperature. It has been observed that these single crystalline microtubes are grown along c-axis. The prominent UV emission and the absence of other visible band in photoluminescence spectrum indicated a good crystallinity and defect-free microstructures. The wettability transition from hydrophobic to hydrophilic was observed after ultraviolet exposure.