Effect of cerium doping to improve the optical and electrical properties of zinc oxide nano structured thin films prepared by spray pyrolysis for transparent conductive oxides applications

Abstract

Using the spray pyrolysis process, undoped and cerium-doped zinc oxide thin films were prepared at 400 °C on a completely cleaned glass substrate with various doping concentrations of Ce (2, 4, 6, and 8 at%). Optical, electrical, structural, surface morphology, surface roughness, chemical composition, and photoluminescence investigations have been performed on these films. According to structural analysis via X-ray diffraction (XRD), the pure and Ce doped ZnO thin films were polycrystalline with a hexagonal wurtzite structure and a (002) plane orientation. The ZnO thin film doped with 6 at% Ce has a minimum of 31.72 nm-sized crystallites. According to the SEM images, the surface morphology of the deposited thin films is porous and results in a uniform distribution of nanoscale grains, which is beneficial for solar applications. The particle size and surface roughness of the produced films decreased with increasing Ce doping, according to the AFM findings. Optical experiments show that all the produced films are transparent in the visible region, and that the transmission is high in 92% for 6 at% of Ce doped ZnO sample, it is appropriate for use in optoelectronic devices. The optical band gap decreases 3.56 eV to 3.11 eV with increasing Ce doping. The PL investigations revealed that the maximum intensity of the UV emission band was 6 at% Ce, indicating an improvement in crystallinity. Electrical studies have shown that with increasing hall mobility, the carrier concentration, conductivity, and resistivity decrease. The lowest electrical resistivity, and highest electrical conductivity for the 6 at% Ce-ZnO sample are 1.21 × 10^− 3 Ω cm, and 825.62 Ω⁻¹ cm^− 1, respectively. These findings indicate that Ce-doped ZnO is a good material for use in transparent conductive oxides applications.