Vapor phase growth of ZnO nanorod-nanobelt junction arrays.

By thermally evaporating a mixture of ZnO, SnO2, and graphite powders at 920 degrees C, large quantities of ZnO nanorods with typical diameters of 20-30 nm are grown secondarily from the surfaces of the ZnO nanobelts to form a nanorod-nanobelt junction array with interesting structural characteristics. A possible growth mechanism of the ZnO nanorod-nanobelt junction arrays with high surface-to-volume ratio is discussed. The ZnO nanorod-nanobelt junction arrays appear an enhanced visible emission due to the high quantity of the surface defects related to oxygen vacancies. The results reported in this paper would lead to new approaches to control the surface structures of ZnO nanomaterials that are critical for their applications, such as chemical sensors.