Controlled growth of well-aligned ZnO nanowire arrays using the improved hydrothermal method

Well-aligned ZnO nanowires were hydrothermally synthesized based on a facile method for preparing the ZnO seed layer which was derived from the combination of a sol-gel process and the spin-coating technique. The effect of the contents of growth solution and the growth duration on the morphology of ZnO nanowires has been investigated.The results indicated that long and vertically aligned ZnO nanowires could be obtained by adjusting the contents of ammonia and polyethyleneimine（PEI） in the growth solution.Under the optimized condition,the length of ZnO nanowires increased fast and almost linearly with the growth duration.After 10 h incubation,ZnO nanowires more than 25μm in length were obtained.By combining the conventional photolithographic method with this hydrothermal approach,long and well-aligned ZnO nanowire arrays were selectively grown on the substrate.In addition,the bottom fusion at the foot of the nanowires has been obviously improved.The results demonstrated that the improved hydrothermal process is favorable to synthesize long and well-aligned ZnO nanowires,and possesses good process compatibility with the conventional photolithographic technique for preparing ZnO nanowire arrays. So it has great potential in applications such as display and field emission devices.