Synthesis and luminescence characteristics of ZnO nanotubes

ZnO nanotubes have been fabricated through a carbon thermal reduction deposition process. Structure characterization results show that the ZnO nanotubes have a single crystalline wurtzite hexagonal structure preferentially oriented in the c-axis. The diameters of ZnO nanotubes are in the range of 90–280 nm and the wall thickness is about 50–100 nm. Room-temperature photoluminescence measurements of the ZnO nanotubes exhibit an intensive ultraviolet peak at 377 nm and a broad peak centered at about 517 nm. The UV emission is caused by the near band edge emission while the green emission may be attributed to both oxygen vacancy and the surface state. Raman and cathodoluminescence spectra are also discussed. Finally, a possible growth mechanism of the ZnO nanotubes is proposed.