Effect of an applied electric field during the oxidation process of zinc thin films on growth and properties of ZnO nanorods

Abstract

In recent years, metal oxide semiconductors have been one of the most remarkable subjects in science and technology. Present research investigates the growth and characterization of Zinc Oxide (ZnO) nanorods (NRs) as one of the metal oxide semiconductors with a broad range of applications. In this work, ZnO NRs preparation includes two steps. In the first step, Zn thin layers were deposited by thermal evaporation method on soda lime glass (SLG) substrate under an electric field of 134 kV/m. The second step contains the oxidation process of the Zn layers under electric fields of 0, 48 and 84 kV/m in air. Then, samples were characterized by X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Field Emission Scanning Electron Microscopy (FESEM), Raman and UV–Visible Spectroscopy. XRD study showed that all samples were crystallized in a hexagonal wurtzite crystal structure. EDX analysis showed that Zn and O atomic ratio, with a good approximation, are close to the ratio expected for ZnO (1:1). FESEM images illustrated that by applying the electric field, diameter of ZnO NRs decreased. Moreover, Raman spectra indicated a shift towards higher wavenumbers due to decreasing the crystallite size and vice versa. In addition, the results obtained from optical measurement demonstrated a reversed behavior of the samples' band gap energy with crystallite size.