Enhanced field emission properties from well-aligned zinc oxide nanoneedles grown on the Au∕Ti∕n-Si substrate

The authors investigated the field emission from vertically well-aligned zinc oxide (ZnO) nanoneedles grown on the $\mathrm{Au}∕\mathrm{Ti}∕n\text{-}\mathrm{Si}$ (100) substrate using metal organic chemical vapor deposition. The turn-on field of ZnO nanoneedles was about $0.85\mathrm{V}∕\mu \mathrm{m}$ at the current density of $0.1\mu \mathrm{A}∕{\mathrm{cm}}^2$ , and the emission current density of $1\mathrm{mA}∕{\mathrm{cm}}^2$ was achieved at the applied electric field of $5.0\mathrm{V}∕\mu \mathrm{m}$ . The low turn-on field of the ZnO nanoneedles was attributed to very sharp tip morphology, and the high emission current density was mainly caused by the formation of the stable Ohmic contact between the ZnO nanoneedles and Au film.