The structure and optoelectronic characteristics of Ni1-xAlxO films synthesized via co-sputtering technique

A new series of Ni1-xAlxO (0 ≤ x ≤ 0.023) films was prepared using the co-sputtering technique. The influence of the partial replacement of Ni-atoms by Al-atoms on the structure, growth orientation, and the lattice strain of NiO crystallites was emphasized. These films exhibit a cubic structure with preferential orientation along the (111) plane. The surface topography was investigated using atomic force microscopy and the lattice vibration was studied using Raman spectroscopy. The optical absorption spectroscopy indicated that the sputtered films depict a direct bandgap energy in the range of 3.31–3.03eV. Likewise, the influence of the inclusion of Al in NiO on the localized states is premeditated in terms of Urbach energy. The photoluminescence measurements divulged that the sputtered films contain oxygen vacancies, nickel vacancies, and interstitial oxygen defects. On the other hand, the incorporation of Al-atoms in the Ni-sites leads to the improvement of the electrical conductivity. The optoelectronic properties of the Ni1-xAlxO (0 ≤ x ≤ 0.023) films were studied. The photo-detection mechanism of the constructed Ag/n-si/Ni1-xAlxO/Ag photodiodes was investigated. It was found that the Ni1-xAlxO (0 ≤ x ≤ 0.023) films exhibited a very fast photo-detection response of 2s and a high sensitivity of 3 × 10−4 A cm−2.sun−1 with high stability and reproducibility.