Effect of film thickness on surface morphology and optical properties of nanostructured Zinc Aluminum Oxide thin films deposited by DC magnetron sputtering

Nanostructured Zinc Aluminum Oxide thin films were deposited on glass substrates by DC reactive magnetron sputtering in an Ar + O₂ gas mixture using commercially available Zn metal (99.999% purity) and Al (99.99% purity) targets. Scanning Electron Microscope (SEM) images of Zinc Aluminum Oxide thin films shows that the grain sizes are in the range of 18-40 nm, while the optical transmittance is found to be dependent on film thickness. Optical constants such as absorption coefficient (α), extinction coefficient (k), and optical band gap (E_g) are evaluated from the transmission spectra.