TEM investigations on ZnO nanobelts synthesized via a vapor phase growth

Unusual ZnO nanostructures have been successfully synthesized via selenium-controlled chemical vapor phase growth on Si (I 11) substrates at about 500degreesC. The microstructure and chemical compositional characteristics of the ZnO nanomaterials have been systematically investigated by means of analytical transmission electron microscopy (TEM), including energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy. Most of the nanostructures have a belt-like morphology with typical widths of similar to150 nm and lengths up to several micrometers. All the investigated materials are found to be stoichiometric ZnO with a hexagonal crystal structure. The growth directions for the nanobelts are found to be [(1) over bar 010] and [(2) over bar 110], respectively. Regular-triangle and needle-like heads with diameters only similar to25-35 nm have been found in the straight nanobelts. High-resolution TEM images indicate that all the nanostructures are single crystals and free of defects. The growth mechanisms of such interesting and unique morphologies are briefly discussed. (C) 2004 Elsevier Ltd. All rights reserved.