Influence of Substrate Temperature on the Properties of Cobalt Oxide Thin Films Prepared by Nebulizer Spray Pyrolysis (NSP) Technique

Abstract

Cobalt oxide thin films are prepared by the nebulizer spray pyrolysis technique using cobalt chloride as the precursor material. The structural, optical, morphological and electrical properties are investigated as a function of substrate temperature (300–450 °C). The X-ray diffraction (XRD) analysis reveals that all the films are polycrystalline in nature, having cubic structure with preferential orientation along the (111) plane. The optical spectra show that the films are transparent (68 %) in the IR region. The optical band gap values are calculated for different substrate temperature. Photoluminescence (PL) spectra of the films indicate the presence of indigo, blue and green emission peaks with an ultraviolet emission peak centered around 368nm. SEM images reveals small sphere-like structures for the prepared Co3O4 films. The maximum conductivity obtained is 1.48 x 10−3 S/cm at 350 °C. The activation energy varies between 0.039 and 0.138 eV for the substrate temperature variation from 300-450 Q°C.