Preparation of vertically aligned ZnO crystal rods in aqueous solution at external electric field

In this study, an external electric field was used to facilitate the growth of vertically aligned ZnO crystal rods on the surface of indium tin oxide (ITO) glass substrates in an aqueous solution. We used Zn(NO3) and C6H12N4 as precursor and reagent. We found that the external electric field generated by DC potential of 5 kV between two electrodes that were placed outside the bottle could facilitate the growth of homogeneous, high density and vertically aligned ZnO crystal rods. Position of the substrate during the growth of crystal was found to be important to obtain well aligned crystal. The crystals that were grown near the negative electrode had the best properties. Photoluminescence measurement at room temperature revealed sharp peaks at around 360 and 380 nm and a broad peak around 420 nm that indicated good properties of ZnO crystals grown with external electric field.