Effect of ZnO Nanoseed Structure on the Growth Orientation of Vertical Array ZnO Nanorods via Hydrothermal Process

Abstract

This paper reports a study of the effect of ZnO nanoseed structure on the growth orientation of ZnO nanorods prepared using a seed-mediated hydrothermal process. In this work, we prepared vertical align ZnO nanorods by a two-step process namely seeding and growth process. ZnO nanoseed on a silicon oxide (SiO2) coated silicon (Si) substrate was deposited by rf- sputtering under argon gas atmosphere at room temperature (ca. 25ºC). The samples were annealed in air at 500 °C for both different annealing times namely 1 and 2 h to obtain nanoseed with varies structure and crystallinity. The ZnO nanorods were then grown from the nanoseed via a hydrothermal process in a growth solution that contained equimolar of zinc nitrate hexahydrate and hexamethylenetetramine (HMT) at 70°C for 4 h. It was found that the durations of annealing treatment on the nanoseed indicated an effective modification on the crystal growth orientation of the nanorods, which preferred well-aligned orientation for shorter annealing time and random growth for longer annealing time. These results should find potential use for manipulating the nanostructure growth of ZnO for applied in current existing application.