Density Control of ZnO Nanorod Arrays by a Solution-Based Growth with a Large Temperature Change for Field Electron Emission Application

A simple, scalable, and cost-effective technique for controlling the growth density of ZnO nanorod arrays based on a large change in reactive temperature is demonstrated. The ZnO nanorods were synthesized using a low temperature (about 70-150degC), solution-based method. We divided the hydrothermally reaction into two temperature stages, a low temperature and a relative high temperature. The density-control technique utilizes a large change in reactive temperature to increase ununiformity among the neighborhood grown ZnO nanorods. The density-controlled arrays were investigated as potential field emission candidates. The field emission results revealed that an emitter density of 6 nanorods mum^-2 generated a high field enhancement factor of 2452. This novel technique shows a possibility of applications in field emission display technology.