The Effect of Growth Temperature on the Characteristics of ZnO Nanorods and Its Optical Properties

Abstract

The aim of this research is to identify the effects of growth temperature on the characteristics of ZnO nanorods synthesized by the hydrothermal method. The Zinc oxide (ZnO) nanorods synthesis was carried out through two steps, consisting of the ZnO seed layer deposition and the ZnO nanorods growth. The ZnO seed layer was prepared by a spin coating method using zinc acetate dehydrate and ethanol on ITO substrate. The following ZnO nanorods growth was performed with the modified hydrothermal method by using hexamethylenetetramine (HMT) as a precursor and zinc nitrate with a molar ratio of 1:1 for 6 hours. A variation of ZnO nanorods growth temperatures of HMT 25 mM and 50 mM was performed in this research. The resulted ZnO nanorods were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to study their structures and morphology. Transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis) were utilized to characterize the optical characteristics of ZnO nanorods. In general, the synthesized ZnO nanorods were found to be oriented on the (100) and (101) planes with diameters ranging from 81 nm until 365 nm and rods lengths up to 5.1 μm. The HMT 50 mM concentration showed that the higher the growth temperature, the larger the sizes of diameter and length of the ZnO nanorods. The ZnO nanorods synthesized by using the 50 mM HMT concentration at 80 oC presented the most favorable result since it had a small size, diameter, and crystallite size with a large energy gap.