Effect of Cu co-doping on the microstructure and optical properties of alumino-zinc thin films for optoelectronic applications

The effect of copper (Cu) co-doping on the microstructure and optical properties of zinc aluminate (AZO) thin films has been investigated. The micro-structure of prepared (Cu/AZO) thin films were described by X-ray diffraction (XRD), Fourier transform-infrared (FTIR), and scanning electron microscopy (HR/SEM). The optical properties are studied via UV-Vis spectrophotometry system. The XRD shows a cubic crystalline phase of the pure film and the addition of Cu did not change the cubic structure in the doped films. The vibrational bands due to the Cu-O bond have been observed at 415 cm−1-851 cm−1 in the FTIR spectra of Cu/AZO films. HR-SEM shows that both pure and doped films are quite homogeneous with good connectivity and the grain boundaries increase with increasing Cu which leads to enhancement of densification and the crystallinity of the films. Optical investigations of Cu/AZO films show a decrease in the bandgap values from 3.87 eV to 3.83 eV with increasing of Cu contents.