Polymeric precursor derived nanocrystalline ZnO thin films using EDTA as chelating agent

In this paper, synthesis of high quality nanocrystalline zinc oxide (ZnO) thin films is presented. A novel polymeric precursor route using ethylene diamine tetraacetic acid (EDTA) as chelating agent for Zn cations has been developed. The synthesized polymeric precursors were spincoated on different surface modified substrates and were annealed at different temperatures. The effect of annealing, over the range of 300–600 °C, on the properties of the ZnO films was investigated. The surface morphology, average crystallite size, degree of crystallization, and optical properties were also investigated. XRD results illustrate that the ZnO thin films are polycrystalline with texturing along the (0 0 2) plane. The thin films are dense, have homogeneous microstructure, with absorption edge at 375 nm, and optical transparency of over 85% in the visible region. The optical band gap energy of ZnO films was found to red-shift on annealing. Room temperature photoluminescence spectra of these films show strong UV emission on annealing.