Mild Hydrothermal Growth of Well-Aligned ZnO Micro/Nano Rods; Study of Seed Layer Effect

Hexagonal micro/nanorods of ZnO were synthesized via mild hydrothermal growth method under different conditions. The growth of the rods was accomplished in two manners: firstly, on bare borosilicate glass, and secondly, on ZnO seed layer prepared by sol-gel spin coating process. Thermal behavior of the precursor solution which was used in spin coating was studied by simultaneous thermal analysis (STA) prior to use. The prepared seed layer was annealed between 400-600°C and the most convenient temperature for the growth of the rods was specified. All the obtained surfaces were studied by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The studies demonstrate that, although with the decrease of concentration of precursor solution on bare borosilicate glass, the diameter of the rods decreases, but the orientation will deteriorate and the density of the rods will decrease. On the other hand, hydrothermal growth on the seed layer causes the decrease in the diameter of the rods, while maintaining the orientation along the c-axis; therefore, the presence of seed layer plays an important role in decreasing the diameter of the rods; so that at a constant concentration, compared with the case without seed layer, we witness an almost 10-times decrease in the diameter of the rods.

Keywords:

Nanorods , Hydrothermal growth , Zinc oxide , Sol-gel