Uniform ZnO nanowire arrays: Hydrothermal synthesis, formation mechanism and field emission performance

Uniform ZnO nanowire arrays were perpendicularly grown on the Zn substrate deposited with the ZnO seed layers by a low-temperature hydrothermal method for the field emission applications. The results indicate that uniform nanowires with the length of about 9 um and diameter of about 70 nm are single crystalline with hexagonal wurtzite structure growth along the c-axis and it enables ZnO nanowires to be a flexible bundling structure. A possible growth mechanism of the ZnO nanowire arrays has been proposed. Raman scatting spectra and photoluminescence spectra confirm that Al-ZnO nanowire arrays have higher structure quality than undoped ZnO nanowire arrays. In addition, the turn-on field and field emission factor were found to be approximately 1.60 V/um and 10835 for the 0.66% Al-ZnO nanowire arrays. It can considerably enhance the field emission performances of the sample after the Al doping, which indicates that Al-doped ZnO nanowire arrays are promising candidate for field emission application.