Optical and structural investigations of dip-synthesized boron-doped ZnO-seeded platforms for ZnO nanostructures

Zinc oxide and boron-doped zinc oxide (B-ZnO) thin films have been dip coated on glass substrates using sol-gel technique. The ZnO solution was prepared using zinc acetate dihydrate (ZAD) as the starting material. Ethanol and citric acid are used in the sol-gel process as solvent and solution stabilizer, respectively. Doping of boron is achieved by adding a proper molar ratio of boric acid (H3BO3) solution to the final ZnO solvent. The optical properties of thin films were investigated using UV-Vis spectrophotometer measurements. Transmittance of undoped ZnO films exhibits high values that are decreasing upon increasing the boron concentration. We found that the index of refraction of undoped ZnO films demonstrates values ranging between 1.6 and 2.2 and increase as B concentration is increased and approximately match those of bulk ZnO. In addition, structural properties were investigated using XRD, SEM and EDAX techniques. Upon annealing, we found that the films exhibit a hexagonal structure and as B concentration increases the grain size increases and the strain decreases. Our results indicate that (B-ZnO) films could be used as seeded platforms for growing nanostructures using hydrothermal method.