Philippine E-Journals

Zinc oxide nanostructures were deposited on glass substrates using ZnSO4 with varying NH4OH concentration via one-stage and two-stage chemical bath deposition (CBD) method. The two-stage process was prepared by pre-treatment of the glass substrates with ZnO colloid powder which were obtained from a previous bath deposition before the CBD takes place. Scanning electron microscope (SEM) images revealed that the two-stage CBD technique yielded a high-density of the ZnO nanostructures as compared to the one-stage process. Moreover, the growth of ZnO nanostructures exhibits a hexagonal structure as revealed by the SEM images. The growth of high-density ZnO nanostructures via two-stage CBD technique can be explained by the presence of the early nucleation of ZnO nuclei provided during the pre-treatment of the substrate with ZnO colloid powders. Furthermore, annealing the as-grown nanostructures at 200oC resulted into the decomposition of Zn complexes forming high-quality ZnO nanostructures and coalescence of smaller ZnO nanostructures to formed bigger ones also occurred. Higher absorption spectra can also be observed from the nanostructures grown via the two-stage process which further confirms the growth of high-density ZnO nanostructures. The calculated energy band gap extracted from the UV-Vis spectra is in good agreement with the reported energy band gap of ZnO nanostructures.