Citrate seed-assisted growth of ZnO microrods

Abstract

Morphology control of the crystal structure is important in semiconductors since their electronic and optical properties can be modulated by changing their size and morphology. In this paper, ZnO microrods were produced using a two-step hydrothermal method. Citrate was added to the seed layer solution as a growth modifier on the first step. Pure ZnO was grown on the seed layers using hydrothermal method for the second step. The main goal is to investigate the citrate seed layer's influence on the ZnO microrods quality. The morphology of seed particles and microrods were investigated by scanning electron microscope (SEM) and the crystallinity was characterized by X-ray diffraction (XRD). SEM images of the seed layers show spherical particles in a mesh-like structure. After the second step, the seed-assisted grown ZnO exhibited rod-like structures. An increase in the sphere’s diameter was observed upon increasing the citrate concentration. Longer rods were observed with the increase of citrate concentration in the seed layer. All peaks in the XRD patterns were indexed to the hexagonal wurtzite structure of ZnO. There were no impurity peaks and secondary phases with different citrate concentrations. Thus, citrate concentration in seed layers plays an important role in altering the morphology of microrods as it controls the crystal's aspect ratio.