Investigation of structural, morphological, and optical properties of (Ni/Co, Fe/Co, and Fe/Ni) co-doped ZnO thin films prepared by sol-gel spin coating technique

• Published in: Journal of sol-gel science and technology Vol. 110; no. 2; pp. 503 - 517
• Main Authors: Ayachi, M., Ayad, F., Djelloul, A., Sali, S., Anas, S., Guezzoul, M., Benharrat, L., Zougar, L., Kermadi, S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2024; Springer Nature B.V
• Subjects: Ceramics; Chemistry and Materials Science; Chromaticity; Coating effects; Cobalt; Color; Composites; Crystal defects; Crystallites; Doping; Emission spectra; Energy gap; Free surfaces; Glass; Glass substrates; Inorganic Chemistry; Iron; Low cost; Materials Science; Morphology; Nanotechnology; Natural Materials; Nickel; Optical and Electronic Materials; Optical properties; Optoelectronics; Original Paper; Particle size; Particle size distribution; Photoluminescence; Photomicrographs; Preferred orientation; Raman spectra; Thin films; Ultraviolet spectra; Zinc oxide; Chromaticity coordinates; XRD; ZnO co-doping; Photoluminescence; Sol-gel spin coating
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-024-06376-y

In this study, undoped and (Ni/Co, Fe/Co, Fe/Ni) co-doped ZnO thin films were deposited on glass substrates by a low-cost sol-gel spin coating technique. The effect of Ni/Co, Fe/Co, Fe/Ni co-doping on the structural, morphological, and optical properties of ZnO thin films was investigated. All films exhibited hexagonal wurtzite nanocrystalline structures with a preferred orientation in the (0 0 2) plane. The crystallite size was found to decrease upon co-doping ranging from 34.4 to 30.2 nm. Raman spectra confirmed the incorporation of all doped ions into ZnO lattice. The morphological analysis of all samples revealed a smooth and crack-free surface, with an average particle size distribution ranging from 50 to 70 nm. All prepared samples showed high transparency in the visible region (~90%) and optical band gap values ranging from 3.263 eV to 3.275 eV, with a high band gap energy of 3.275 eV for the Fe/Co co-doped ZnO thin films. The PL spectra of co-doped samples exhibited a relatively similar features of emission spectra, in both ultraviolet (UV) and visible regions except for Fe/Co-ZnO presented a quenching of visible emission. The systematic investigation into the possible mechanisms underlying defect luminescence in each sample revealed that co-doping with Fe/Ni and Ni/Co lead to a slight increase in the abundance of O i in the ZnO film. The examination of the chromaticity color coordinates showed that only co-doping with Fe/Co induces a shift to a different color region on the CIE chromaticity diagram. The properties of prepared ZnO thin films demonstrated their suitability for light-emitting and optoelectronic applications. Graphical Abstract Highlights Undoped and (Ni/Co, Fe/Co, Fe/Ni) co-doped ZnO thin films were deposited on glass substrates by a low-cost sol-gel spin coating technique. The structure, surface morphology, transmittance, and photoluminescence were studied in detail. X-ray diffraction study revealed the formation of nanocrystalline thin films highly oriented along the c-axis in the (002) plane with a pure hexagonal wurtzite structure. SEM micrographs revealed a granular surface that was free of cracks and had a homogeneous distribution of particles with an average particle size between 50 and 70 nm. All prepared samples showed high transparency in the visible region (~90%) and optical band gap values ranging from 3.263 eV to 3.275 eV.