Effect of Growth Temperature on Morphological, Structural, and Optical Properties of ZnO Nanorods Using Modified Chemical Bath Deposition Method

Zinc oxide (ZnO) nanorods (NRs) have been investigated as a function of different growth temperature using modified chemical bath deposition (M-CBD) method. In this study, air bubbles were utilized inside the growth solution as an original modified process. The synthesis of ZnO NRs was carried out through two steps. The first step was deposition of the ZnO seed layer on the glass substrate, while the second step was growing the ZnO NRs on the seeded substrate. The impacts of the growth temperature on the morphology and crystal structure of the ZnO samples were investigated using field emission scanning electron microscopy and x-ray diffraction. UV–Vis spectroscopy was also utilized to characterize the optical properties of the ZnO NRs. The results showed that the growth of the ZnO samples is a NRs-like shape. The ZnO samples possess the hexagonal wurtzite structure with high crystal quality, and no other phases from the impurity were observed. Additionally,the ZnO NRs were found to be well oriented along te (002) planes with diameters ranging from 71 nm to 328 nm and length from 294 nm to 2475 nm, while the aspect ratio was up to 25 with different growth temperatures. However, the UV–Vis spectrum showed that the optical transmittance of the ZnO NRs dropped from ~ 66% to ~ 3.3%, and the absorption band edge had been shifted to a lower-energy region as the growth temperature increased from 65°C to 95°C. This is possibly due to the scattering increase and absorption light from voids, grain size, and thickness of the ZnO NRs. Therefore, it has been demonstrated that the ZnO NRs grown by the M-CBD method at a growth temperature of 95°C gives the most favorable result, since the NRs possess the optimum, homogenous, and uniform distribution with a higher aspect ratio, crystal quality, crystal size, and band gap energy.