Physical properties evaluation of various substrates coated cupric oxide thin films by dip method

In this work, we have reported on dip coated cupric oxide (CuO) films prepared at various substrates such as glass, indium doped tin oxide (ITO), silicon and polymer, respectively. The film thickness was estimated using surface profilometer and found to be in the range of ∼520–640 nm. The dip coated films structural, morphological, optical and topographical properties were studied. The dip coated CuO structural properties were studied using X-ray diffraction (XRD) studies. X-ray diffraction patterns revealed that the deposited films were polycrystalline monoclinic structure with predominant orientation of (−1 1 1) crystallographical lattice plane. The microstructural properties of crystallite size (D), dislocation density (δ), microstrain (ε) and stacking fault probability (α) for preferential orientations were calculated and discussed in detail. The surface morphology and elemental analyses were characterized using scanning electron microscopy and energy dispersive analysis by X-ray spectroscopy, respectively. Morphological studies revealed that the uniform morphology with nano sheet shaped grains covered the entire surface of the film prepared at glass substrate. Optical properties of CuO films were analyzed by transmission and linear absorption coefficient using UV–Vis–NIR wavelength region. Tauc’s plot was used to determine the band gap of the films and found to be 1.08 eV for glass substrate. The optical constants such as optical conductivity (σ), average excitation energy (Eo), oscillator strength (Ed), effective mass (m∗), plasma frequency (ωp), static dielectric constant (ε∞) and carrier concentration (N) were estimated using an approximation algorithm developed from established procedures using transmittance spectrum of the thin films. Consequently, it was determined that various substrate has a strong effect on the structural, surface, optical and morphological properties of cupric oxide films.

► Stoichiometric CuO thin films are successfully synthesized by dip coating method.
► The effects of various substrates on film properties are analysed.
► Improved microstructural properties are achieved for dip coated films.
► Lower band gap (1.08 eV) suitable for solar cell applications is achieved.