Cu doping induced structural and optical properties of bimetallic oxide nanodots by the vertical spark generation

Abstract

Undoped ZnO and Cu doped ZnO nanodots (NDs) were synthesized by the modified sparking technique with the Zn and Cu metal electrode pairs such as Zn–Zn, Zn–Cu and Cu–Cu. The effect of deposition geometry on the structural, optical properties and band gap energy were examined. The X-ray diffraction (XRD) analysis demonstrates that the nanodots have the hexagonal wurtzite structure, and visible considerable shift in the peaks position can be linked with the influence of Cu. However, when copper electrode was used, some copper oxide phases, metallic copper and paramelaconite phases were observed. From the results, the average diameters of metal oxide nanodots are about 25 nm and 50 nm which were obtained by using Cu–Cu and for Zn–Zn electrodes respectively from the scanning electron microscopy (SEM) analysis. When the Zn–Cu electrode pairs were used, the mixture of nanorod and nanodots appeared. It was observed that the island growth occurs in the horizontal geometry of electrode pairs and the growth metal oxide species are more strongly bonded to each other than to the substrate. But, these nanodots have more uniform distribution in the vertical geometry of electrodes. Optical studies indicated that the band gap decreased (red shift) when the Cu electrode was used.