Aluminum foil mediated noncatalytic growth of ZnO nanowire arrays on an indium tin oxide substrate

Vertically grown ZnO nanowires are synthesized on an indium tin oxide (ITO) substrate via a vapor transport method. The arrays of ZnO nanowire are spontaneously produced from the vapor of a 1: 1 mixture of ZnO and Zn powders with no metal catalyst. The key to this synthetic process lies in covering the ITO substrate with an aluminum foil that has a small hole in order to maintain an optimum level of supersaturation. Transmission electron microscopy and X-ray diffraction confirm the single crystalline nature of the wurtzite ZnO nanowires. This is the first report of vertically grown single-crystalline ZnO nanowires on an ITO substrate by gas phase synthesis. Direct growth of vertical ZnO nanowires on a conducting and transparent ITO substrate would find useful applications in field emission displays and solar cells.