Highly Transparent Nano-Needle ZnO Prepared by Successive Ionic Layer Adsorption and Reaction Method

Abstract

In this study, well-aligned ZnO nano-needle arrays were synthesized on glass substrates using the two-step successive ionic layer adsorption and reaction (SILAR) method in ethylene glycol. The ZnO seed layer was first formed at a low temperature (95 • C), and the subsequent growth of highly oriented nano-needle arrays occurred at a higher temperature (145 • C). Growing the seed layer at 95 • C led to the formation of separated needle-like nanostructures instead of inseparable rod-shape structures. The ZnO nanoneedle arrays crystallized along the c-axis with a Wurtzite hexagonal structure. The optical transmittance of the nano-needle arrays was greater than 90% in the visible spectrum. The band gap of 3.38 eV corresponds to that of as-grown ZnO nano-needle arrays. Due to the simplicity, time-efficiency, and low-temperature processes involved in the two-step SILAR method, it is a promising fabrication technique for highly transparent ZnO nano-needle arrays.