Some Properties of Manganese Oxide (Mn-O) and Lithium Manganese Oxide (Li-Mn-O) Thin Films Prepared via Metal Organic Chemical Vapor Deposition (MOCVD) Technique

Single solid source precursors, Manganese acetylacetonate (Mn(C5H7O2)2) and Lithium manganese acetylacetonate (Li-Mn(C5H7O2)3) were prepared and thin films of Mn-O and Li-Mn-O were deposited on sodalime glass substrates using MOCVD (Metal organic chemical vapour deposition) technique by pyrolysing Mn(C5H7O2)2 and Li-Mn(C5H7O2)3 respectively at a temperature of 420 ° C for approximately 2 h. The films were characterized using RBS (Rutherford backscattering spectroscopy), SEM (Scanning electron microscopy), XRD (X-ray diffraction), van der Pauw method and Ultraviolet-Visible Spectroscopy. The compositional analysis showed that the Mn:O ratio is 0.2:0.8 while that of Li:Mn:O was found to be 0.47:0.24:0.29. SEM micrograph showed that Mn-O film is composed of hollow needle-like rods with coarse, continuous and uniformly distributed polycrystalline grains rod-like, having average grain size estimated to be below 10µm while those of Li-Mn-O showed that the film is dendritic and polycrystalline in which some of the grains were found to lump together. XRD also showed the polycrystalline nature of the films with orthorhombic MnO2 and orthorhombic Li3MnO4 structures for Mn-O and Li-Mn-O thin films respectively. Results of characterization also showed that the films are semiconducting, highly absorbing in the visible region with absorption edges observed at wavelengths of 525 nm and 550 nm, corresponding to direct optical band gaps of 2.36 eV and 2.25eV for Mn-O and Li-Mn-O thin films respectively.