ZnO nanowires formed on tungsten substrates and their electron field emission properties

Using a vapor transport method, ZnO nanowires were selectively synthesized both on tungsten tips as electron field emitters and on tungsten plates with designed patterns. Control of the growth locations of the nanowires was accomplished by selectively positioning a thin film of Au catalyst. The angular intensity and fluctuation of the field emission current from the ZnO nanowires synthesized on tungsten tips have been demonstrated to be similar to those of carbon nanotubes. A self-destruction limit of ∼0.1 mA/sr for angular intensity was observed, and the power spectra showed a 1/f3/2 characteristic from 1 Hz to 6 kHz.