Growth behavior and field emission property of ZnO nanowire arrays on Au and Ag films

We propose a facile method to control the growth and areal density of zinc-oxide (ZnO) nanowire arrays using gold or silver films deposited on aluminum-doped ZnO (AZO) layers coated on glass substrates. Nanowires exceeding 5 μm in length grew on both the glass/AZO-layer and on the glass/AZO-layer/Au-film where the areal array density was controlled primarily by changing the annealing temperature. In contrast, the nanowire arrays grew only on the AZO surface but not on the Ag film owing to the formation of an Ag-oxide layer. We fabricated field emitter devices with density controlled ZnO nanowire arrays and low turn-on electric field of ∼6 V/μm and a field enhancement factor of up to 1188 were obtained with density controlled ZnO nanowire arrays.