Structural and physical properties of Mg-doped CuCoO2 delafossite thin films

In this work, Mg-doped CuCoO2 (CCO) delafossite oxide was synthesized by a low-cost technique, namely spray pyrolysis. We investigated the effects of Mg doping on the structure, morphology, chemical composition, and optical properties of CCO with different percentages (1%, 2%, 3%, 4%, 5%). Using X-ray diffraction analysis, we observed an excellent agreement without any impurities in the Mg-doped CuCoO2 delafossite structure. To analyze the variations caused by doping on the quality, we examined the morphology of the produced films using field emission scanning electron microscopy. The deposited samples exhibited different textures and surfaces that were evenly distributed throughout the substrate. Furthermore, we utilized a transmission electron microscope to examine the Mg-doped CuCoO2 films. The CuCo1-xMgxO2 with x = 0.01 delafossite displayed excellent crystallinity. The results indicated that the fringe distances of 0.23 nm, 0.85 nm, and 0.16 nm corresponded to the spacings of the CuCoO2 lattice planes (110), (222), and (332) respectively. Optical properties were measured using UV–Vis spectroscopy at room temperature, revealing weak visible light absorption. It was found that CuCo1−xMgxO2 could be transparent to photons with energies in the visible range. Additionally, the band gap decreased in parallel with increasing Mg doping until a percentage of 3% (0.03), where a value of Eg = 1.75 eV was obtained.