Comparative studies of Cobalt Oxide (CoO) and Copper Oxide (CuO) thin films deposited by improved electroless chemical bath technique at 320K

Abstract

Semi conducting thin films of cobalt oxide (CoO) and copper oxide (CuO) were successfully deposited on glass slides at 320K and pH values of 7, 9 and 11 by electroless chemical bath deposition method. Ethylenediamine-tetra acetate (EDTA), another complexing agent, with pH oppose that of bath reagents was added to bath constitutions to enhance control and stabilize the deposition bath pH at different values suitable for film deposition. X-ray diffraction method was used to confirm the depositions. Electron micrographs of the films reveal uniform surface depositions. Absorbance (A) spectra data were measured by a single beam spectrophotometer at wavelength range 200nm to 900nm. Other optical and solid state properties were calculated from the data and compared with other deposited thin films. Average optical and solid state properties of CoO thin films include absorbance ranging from 0.051 to 0.212, transmittance 0.614 to 0.889, refractive index 1.64 to 2.43, electrical conductivity 0.43 to 0.58 (ohm-cm)^-1, film thickness 0.052 to 0.216μm and band gap 2.36 to 2.75 +0.05eV. For CuO thin films the absorbance ranges from 0.084 to 0.112, transmittance 0.646 to 0.824, refractive index 1.82 to 2.36, electrical conductivity 0.48 to 0.62 (ohm-cm)^-1, film thickness 0.003 to 0.051μm and band gap 1.75 to 2.45 +0.05eV. Films with refractive index lower than 1.9 could be used in antireflection coatings, eyeglass coating and solar thermal control coatings. Those with refractive index greater than 1.9 could be useful in construction of poultry houses and anti dazzling coatings. The films could be employed in solar cells.

Journal of the Nigerian Association of Mathematical Physics Vol. 9 2005: pp. 519-528