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Al doped ZnO thin films were deposited using sol-gel spin coating method onto ITO coated glass substrate and their structural, optical and electrical properties were investigated through XRD, UV–Visible spectroscopy and two probe set up, respectively. Structural studies reveal that, undoped films are polycrystalline in nature where as Al doping show significant preferred orientation along c – axis. Optical studies reveal >90% transparency in films and also an increase in the band gap energy with Al doping, due to increase in the carrier concentration of the Al doped ZnO and the mechanism is well explained on the basis of Burstein – Moss effect. In addition, Urbach energy was estimated and found to increase with increase of Al content, indicating decrease in the defect density of the films, in supportive with the XRD results. Also, sheet resistance of Al doped ZnO films found to decrease with increase in Al concentration. The investigated results confirm that Al doped ZnO films are feasible and potential candidates for TCO applications. [ABSTRACT FROM AUTHOR]

Optically transparent Zn 0.97-x Al 0.03 Ni x O thin films were prepared using spin coating technique. The role of Ni concentration on the structural, microstructural, composition and optical properties were studied by means of XRD, SEM-EDS, RAMAN, UV–Visible spectroscopy. The prepared preferred crystalline orientation along the (002) plane (c -axis) with Ni concentration is seen in the prepared films. The findings of FESEM –EDX demonstrates the homogeneous, uniform and smooth texture of the prepared films with strong adherence to the glass substrate and the presence of nominal values of elements. In addition, the findings of Raman also confirm the absence of Ni related impurity phases. Furthermore, Raman peak shift and intensity variations of Raman spectra suggests that the prepared films have a high degree of crystallinity with lower residual stresses. Optical results suggested that spin coated thin films have optical transparency nearly 90% in the visible wavelength region. It was also observed that the energy bang-gap decreases with the concentration of Ni ions in the host ZnO matrix. Results examined indicate that spin-coated thin films are possible candidates for TCO applications. • Transparent Ni co-doped Al:ZnO thin films are prepared by spin coating method. • Films exhibits preferred crystalline orientation along (002) plane. • Films are transparent with ~90% transparency in the visible region. • Band gap narrowing effect is observed with Ni concentration. [ABSTRACT FROM AUTHOR]

• NiO and Sn doped NiO thin films deposited using simple sol–gel spin coating technique. • Crystallite size decreses with dopant concentration demonsrating high surface to vlume ratio. • The prepared films surface morphology observed to be suitable for enhanced gas sensitivity. • Synthesized nanostructured films of NiO and Sn doped NiO exhibit high potential for ammonia sensing at room temperature. In this study, we detail the fabrication of Sn-doped nickel oxide thin films using the spin-coating technique, elucidating the impact of Sn doping on structural, optical, and gas sensing properties. Systematic analysis via XRD, SEM, AFM, and UV–Visible spectroscopy delves into the structural and optical characteristics of the films. Notably, gas sensing capabilities, specifically towards NH 3 , are investigated. XRD analysis reveals the polycrystalline nature of NiO thin films, with crystallinity diminishing as Sn concentration increases. SEM and AFM analyses highlight a uniform film surface with spherical-shaped particles, and increased surface roughness with higher Sn content, a crucial factor for gas sensing applications. Raman analysis showcases first-order phonon modes of vibrations of Ni-O, while optical studies affirm the films' transparency in the visible wavelength. Notably, in ammonia gas sensing tests at room temperature, the 8 mol% Sn-doped NiO thin film exhibits an exceptional response of 3200 %, with a rapid 40-second response time and a 25-second recovery time at a 150 ppm concentration of ammonia gas. These findings suggest that Sn-doped NiO thin films hold promise as effective gas sensors for NH 3 detection. [ABSTRACT FROM AUTHOR]