Growth of Vertically Aligned ZnO Nanobelt Arrays on GaN Substrate

Uniformly aligned ZnO nanobelt (NB) arrays have been grown on a (0001) GaN substrate without foreign catalyst such as Au. The NBs mainly grew along [011̅3] at beginning when the temperature was relatively low, then switched to [011̅0] at high temperature, and finally switched to [011̅3] when the temperature was lowed. The alignment of the NBs was due to not only the epitaxial orientation relationship with the substrate but more importantly the presence of metallic Zn nanoparticles at the tip of the ZnO NBs, which were produced by reduction of ZnO source material. The Zn nanoparticle has a fixed orientation relationship with the ZnO NB, indicating that the growth follows the self-catalyzed vapor−liquid−solid process.