Enhancing low-temperature sensor applications: Synergistic effects of Ni doping and SnO2 interlayer on spin-coated ZnO thin films on glass substrate

• Published in: Optical materials Vol. 157; p. 116272
• Main Authors: Rezoug, Maya Hanane, Zegadi, Chewki, Nouri, Abdelkader, Hamdadou, Nasr-Eddine, Guezzoul, M'hamed
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2024
• Subjects: Interlayer; Nickel doping; SnO2; Sol-gel spin coating; Synergistic impact; Temperature sensor; ZnO; Nickel doping; SnO2; Temperature sensor; ZnO; Synergistic impact; Interlayer; Sol-gel spin coating
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2024.116272

This study investigates the effects of Nickel doping and a SnO2 interlayer on the structural, morphological, optical, and electrical properties of ZnO thin films. Undoped and Ni-doped ZnO films were fabricated on glass substrates, with and without an SnO2 interlayer, using the sol-gel spin coating method. The samples—denoted as ZG (undoped ZnO), NZG (Ni-doped ZnO), ZSG (undoped ZnO with SnO2 interlayer), and NZSG (Ni-doped ZnO with SnO2 interlayer)—underwent comprehensive characterization via XRD, AFM, PL, UV–Vis spectroscopy, Hall effect measurements, Hot probe, and Two-point method. XRD analysis confirmed successful Ni incorporation and enhanced ZnO crystallinity, particularly in the presence of the SnO2 interlayer. AFM analysis revealed improved grain distribution and size due to the synergistic effects of Ni doping and the SnO2 interlayer. UV–Vis results indicated significant impacts on transparency and the Urbach energy, with Ni doping alone broadening the bandgap. PL measurements showed that the synergistic effects quenched UV luminescence associated with the glass substrate, enhancing visible luminescence. Chromaticity analysis suggested that ZSG and NZSG samples are suitable for warm blue region applications. Electrical measurements revealed n-type conductivity across all films except NZG, with Ni doping increasing resistivity. Additionally, the ZSG (PTC) sensor exhibited a slightly higher sensitivity (0.3852 Ω/°C) compared to the NZSG sensor (0.3782 Ω/°C), with a similar trend observed in NTC sensors. These findings suggest that Ni-doped ZnO films with SnO2 interlayers could potentially serve as thermistors and RTDs, offering promising applications in temperature sensing and optoelectronics.
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•Enhanced ZnO thin film properties with Ni doping and SnO2 interlayer.•Improved crystallinity and surface quality.•Reduced transparency and increased visible luminescence.•Effective NTC and PTC behaviors for temperature sensor applications.•Supports the development of stable, high-performance sensors.