Heterogeneity of photoluminescence properties and electronic transitions in copper oxide thin films: A thickness dependent structural and optical study

In the present article, copper oxide thin films of different thicknesses were deposited on glass substrates by dc reactive magnetron sputtering. X-ray diffraction pattern revealed that the films crystallize in tenorite (CuO) phase. We have observed the presence of different structural disorders in the films through the photoluminescence (PL) spectra. The spectra enabled us to analyse the possible recombination mechanisms in CuO thin films. The relationship between refractive index and porosity of the film surface was studied and thicker films have shown higher percentage of porosity compared to that of thinner films. The optical constants of the film were computed with the help of absorbance and reflectance spectra. The optical band gap seems to depend on the particle size and the strains present in the film. The thickness dependence of the films on their structural, morphological, optical and photoluminescence properties are described.