Surface structure optimization for cost effective field emission of zinc oxide nanorods on glass substrate

• Large scale arrays of ZnO nanorads on glass substrate have been fabricated.
• The effects of seed layer thickness on density of ZnO nanorod were investigated.
• The field emission property of a single ZnO nanorod depends upon their aspect ratio.
• The aspect ratio is essentially attributed to the change of the field enhancement factor.
• Both changes in density and aspect ratio were found to obviously affect field emission.

Density and aspect ratio engineering of ZnO growth are very attractive for many applications. In this article, we report the effect of seed layer thickness on the density of zinc oxide (ZnO) nanorod arrays on glass substrate without any conductive electrode in a low temperature (85 °C) chemical bath deposition process. It was demonstrated that when the seed-layer thickness changes from 50 to 200 nm, the nanorod density increases from 7.8 × 106 to 6.5 × 108 cm− 2. In addition, this density variation is accompanied by the change of both diameter and height of the nanorods. The results on different nanorad arrays showed that the properties of field emission follow the Fowler–Nordheim law. The variation of the density and the aspect ratio was found to have a serious effect on the field emission characteristics. Finally, an optimal density of 107/cm2 and aspect ratio of 46.48, demonstrated the best field emission profile. The field emission property of a single ZnO nanorod depends mainly upon their aspect ratio, which is essentially attributed to the change of the field enhancement factor in a single ZnO nanorod.