Realization and manipulation of ZnO nanorod arrays on sapphire substrates using a catalyst-free metalorganic chemical vapor deposition technique

Single-crystalline ZnO nanorod arrays (ZNRs) were grown by metalorganic chemical vapor deposition on ZnO buffer/sapphire substrate without using any metal catalyst. The density of vertically aligned ZNRs was found to govern by the morphology and thickness of buffer layer. That is to say, the ZnO buffer layer can be used as the nucleation template to control the growth direction and density of the ZNRs. In addition, by controlling the diethyl zinc flow rate, we can manipulate the size, crystal, and optical quality of ZNRs. Finally, the possible growth mechanism of ZNRs was discussed in detail.