Structural, optical, and electrical evolution of sol–gel-immersion grown nickel oxide nanosheet array films on aluminium doping

We developed aluminium (Al)-doped nickel oxide (NiO) nanosheet arrays film on the indium-doped tin oxide (ITO) substrate via sol–gel immersion method using nickel nitrate hexahydrate and aluminium nitrate nonahydrate as precursor and dopant materials, respectively. The Al-doping concentrations were varied from 0 to 2 at.%. Uniform Al-doped NiO nanosheet array films were observed on the substrate; the denser and smaller size of the NiO nanosheets were obtained at higher Al-doping concentrations. The growth mechanism was proposed. The crystallinity of Al-doped NiO nanosheet deteriorated at higher doping concentration. Meanwhile, the crystallite size, lattice parameter, and interplanar spacing were reduced with the doping quantity. The compressive strain, tensile stress, dislocation density, and band gap of the Al-doped NiO upsurged at higher doping concentration. The current–voltage measurement results revealed that the resistivity increased after the doping process up to 2 at.%. The Raman spectra showed that the doped samples exhibit blue-shift and decreased intensity of the Raman peaks.