Analyzing Process of High Density and Uniformity of ZnO Nanocolumns

Abstract

This research investigated the process of growing high-density and uniformity of zinc oxide (ZnO) nanocolumns across coadte indium tin oxide (ITO)/Glass substrates by hydrothermal process. The synthesis was carried out via a two-step process: the deposition of a ZnO seed layer using a spin-coating method, followed by the hydrothermal growth of the ZnO nanocolumns. The precursor solution for the seed layer consisted of zinc acetate dihydrate and monoethanolamine (MEA) at a 1:1 ratio with concentrations of 10 mM and 14 mM. The spin coating was performed at 2500 rpm for 4 cycles at room temperature, followed by an annealing process at 300°C for 1 hour. Subsequently, the nanocolumns were hydrothermally grown using an aqueous solution of zinc nitrate hexahydrate (ZNH) and hexamethylenetetramine (HMTA) with varying the ratios from 1:1 to 1:3 at 90°C for 6 hours. The surface morphology of the seed layers and nanocolumns was characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD) for crystallographic structure, water contact angle measurements for surface wettability, and UV-Vis spectrophotometer for light transmission and energy bandgap. The results demonstrated that the successfully deposited seed layer on the ITO/glass substrate facilitated the continuous and uniform growth of high-density ZnO nanocolumn in an array across the entire substrate. Furthermore, XRD analysis confirmed that the synthesized nanocolumns exhibited high crystallinity with a strongly preferred orientation along the (002) plane. Moreover, the wettability investigation revealed that the ZnO nanocolumns exhibited hydrophilic characteristics, which are likely strongly influenced by their surface morphological features. The light transmission is about 95% and has the energy bandgap of about 3.27 eV that is in the range of ZnO materials