Ezekiel Oladele Bolarinwa Ajayi

Preparation and characterization of MOCVD thin films of indium tin oxide

Abstract Indium Tin Oxide (ITO) was deposited by pyrolysis of mixed metal acetylacetonate (a single solid-source precursor). This study demonstrates that the properties of the as-deposited film depend on the deposition temperature. Films with a resistivity of 7.2×10 −4 Ω cm , a visible transmission of over 80%, and a direct optical energy gap of 3.76 eV were deposited.

Preparation and optical characterization of MOCVD ZnCdInS thin films

Abstract The precursor, bis-(morpholinodithiocarbamate-s,s′)-Cd–Zn–In has been prepared and pyrolyzed to obtain ZnCdInS thin films. The results of the compositional studies carried out using RBS and EDXRF were found to be complementary. An optical band gap of 2.53 eV was obtained from both absorbance and PL measurements.

Preparation and characterization of pyrolytically deposited (Co–V–O and Cr–V–O) thin films

The metal acetylacetonates of vanadium, cobalt and chromium were prepared from commercial reagents. The corresponding metal acetylacetonates were mixed in desired ratio and deposited on soda lime glass substrate by metal organic chemical vapor deposition technique. Mixed oxides thin films with atomic composition Co VO and Cr V O were obtained. A combination 0.31 1.37 5 0.5 2 5 of Rutherford backscattering spectroscopy and energy-dispersive X-ray fluorescence was used for the transition element identification and atomic compositional study of the thin films. The thickness of the Co – V– O and Cr – V– O thin films was 166 and 127 nm, respectively. The optical spectra of the films were obtained using a Pye Unicam SP8-400 spectrophotometer in the ultraviolet yvisible region. The result of the spectral analyses gave the optical bandgap energy of the materials. The temperature dependence of the electrical resistivity measured using the Van der Pauw method indicated that the materials are semiconducting. Their activation energy was obtained from plots of the natural logarithm of conductivity vs. the reciprocal of temperature. The sign of the thermopower shows that both materials are p-type semiconductors. � 2002 Elsevier Science B.V. All rights reserved.

Optical characterization of pyrolytically deposited ZnxCd1−xS thin films

Abstract The precursor bis-(morpholinodithioato-s,s′)–Cd–Zn was prepared and the thin films of Zn x Cd 1− x S deposited on sodalime glass substrate. A direct optical energy gap of 2.63 eV was obtained from the analysis of the absorption spectrum. The photoluminescence spectrum shows shift in the energy of the primary emission peaks as a function of the excitation energy. The shift was explained as due to the quantum size effect in nanometer thick polycrystalline films. Energy Dispersive X-ray Florescence (EDXRF) confirms the elemental composition of both the precursor and the films.

Preparation and characterization of MOCVD thin films of zinc sulphide

Abstract Thin solid films of stoichiometric zinc sulphide on soda lime glass and stainless steel was deposited by the pyrolysis of bis-(morpholino dithioato-s,s′)zinc (C10H16N2O2S4Zn) (a single solid source precursor). The band gap of 3.67 eV was obtained by optical absorption spectroscopy. The composition, stoichiometry and thickness were determined by energy dispersive X-ray fluorescence (EDXRF) and Rutherford backscattering spectroscopy (RBS) and the absence of organic remnants in the film is demonstrated by IR spectroscopy and RBS.

Synthesis and Some Properties of Metal Organic Chemical Vapour Deposited Molybdenum Oxysulphide Thin Films

of oxygen. The large amount of oxygen was attributed to the large abundance of oxygen in the starting material. A direct optical energy gap of 3.31 eV was obtained from the analysis of the absorption spectrum. The scanning electron microscopy (SEM) micrographs of the fllms showed that the fllms were continuous and porous. An estimated average size of the grains was below 5 „m. X-ray difiraction (XRD) showed that the deposited fllms were crystalline in nature.

Preparation and characterization of undoped zinc oxide and uranium doped zinc oxide thin films

Doped and undoped zinc oxide thin films were deposited by metallorganic chemical vapour deposition technique, which has been reported previously. The undoped zinc oxide thin films were deposited from the pyrolysis of zinc acetate while those of uranium-doped zinc oxide were deposited from uranyl zinc acetate. The scanning electron microscope micrograph shows that the ZnO thin film has polycrystalline structure. The band gaps of the undoped ZnO and uranium doped ZnO thin films were determined using optical technique and found to be 3.24 and 3.16 eV respectively.

Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

Abstract Lithium manganese oxide thin films were deposited on sodalime glass substrates by metal organic chemical vapour deposition (MOCVD) technique. The films were prepared by pyrolysis of lithium manganese acetylacetonate precursor at a temperature of 420 °C with a flow rate of 2.5 dm3/min for two-hour deposition period. Rutherford backscattering spectroscopy (RBS), UV-Vis spectrophotometry, X-ray diffraction (XRD) spectroscopy, atomic force microscopy (AFM) and van der Pauw four point probe method were used for characterizations of the film samples. RBS studies of the films revealed fair thickness of 1112.311 (1015 atoms/cm2) and effective stoichiometric relationship of Li0.47Mn0.27O0.26. The films exhibited relatively high transmission (50 % T) in the visible and NIR range, with the bandgap energy of 2.55 eV. Broad and diffused X-ray diffraction patterns obtained showed that the film was amorphous in nature, while microstructural studies indicated dense and uniformly distributed layer across the substrate. Resistivity value of 4.9 Ω·cm was obtained for the thin film. Compared with Mn0.2O0.8 thin film, a significant lattice absorption edge shift was observed in the Li0.47Mn0.27O0.26 film.

Preparation and characterization of metallorganic chemical vapour deposited LixMoyOz using a single source solid precursor

Thin films of LixMoyOz have been deposited on glass substrate in a one step chemical vapour deposition using a single source solid precursor. The films were characterized using Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffractometry, Scanning Electron Microscopy (SEM), Impedance Spectroscopy (IS), van der Pauw conductivity measurement and Ultraviolet-Visible Spectroscopy. Results of the characterization showed that the films are dendritic, polycrystalline and semiconducting with an optical transition energy of 3.0 eV. IS characterization gave a semicircle in the complex impedance plot. The conductivity vs. temperature plot showed a transition at 450 °C and also a hysteresis. Analysis showed the film to be mixture of phases.