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. 2022 Sep 19;12(18):3244.
doi: 10.3390/nano12183244.

Multifunctional Zn-Doped ITO Sol-Gel Films Deposited on Different Substrates: Application as CO2-Sensing Material

Mariuca Gartner  1 , Mihai Anastasescu  1 , Jose Maria Calderon-Moreno  1 , Madalina Nicolescu  1 , Hermine Stroescu  1 , Cristian Hornoiu  1 , Silviu Preda  1 , Luminita Predoana  1 , Daiana Mitrea  1 , Maria Covei  2 , Valentin-Adrian Maraloiu  3 , Valentin Serban Teodorescu  3 , Carmen Moldovan  4 , Peter Petrik  5   6 , Maria Zaharescu  1
Affiliations

Multifunctional Zn-Doped ITO Sol-Gel Films Deposited on Different Substrates: Application as CO2-Sensing Material

Mariuca Gartner et al. Nanomaterials (Basel). .

Abstract

Undoped and Zn-doped ITO (ITO:Zn) multifunctional thin films were successfully synthesized using the sol-gel and dipping method on three different types of substrates (glass, SiO2/glass, and Si). The effect of Zn doping on the optoelectronic, microstructural, and gas-sensing properties of the films was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE), Raman spectroscopy, Hall effect measurements (HE), and gas testing. The results showed that the optical constants, the transmission, and the carrier numbers were correlated with the substrate type and with the microstructure and the thickness of the films. The Raman study showed the formation of ITO films and the incorporation of Zn in the doped film (ITO:Zn), which was confirmed by EDX analysis. The potential use of the multifunctional sol-gel ITO and ITO:Zn thin films was proven for TCO applications or gas-sensing experiments toward CO2. The Nyquist plots and equivalent circuit for fitting the experimental data were provided. The best electrical response of the sensor in CO2 atmosphere was found at 150 °C, with activation energy of around 0.31 eV.

Keywords: Zn-doped ITO thin films; electrical properties; gas testing; microstructure; optical properties; sol–gel films.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flowchart for the preparation of the ITO:Zn thin films.
Figure 2
Figure 2
SEM micrographs at different magnification: (a,b) 100,000×, surface top view; (c,d) 500,000×, edge view. (a–c) ITO:Zn and (b–d) undoped ITO films. The darker gray area below the film edge in (c,d) is the underlying Si substrate.
Figure 3
Figure 3
EDX spectrum of ITO:Zn film on Si: (a) full spectrum, showing the Si Kα line from the substrate and small contributions of the O Kα, In M, In Kα, Sn Kα, and Zn Lα peaks from the film; (b) magnified view of the peaks from the film.
Figure 4
Figure 4
CTEM images (a,d), HRTEM images (b,e), and EDX line scan in HAADF image (c,f) for ITO and ITO:Zn films, respectively.
Figure 5
Figure 5
XRD patterns of ITO films undoped and doped with 4% Zn deposited on (a) glass, (b) Si, and (c) SiO2/glass.
Figure 6
Figure 6
Topographic 2D AFM images at the scale of 1 µm × 1 µm, for undoped (first row) and ITO:Zn films (second row) deposited on three different substrates: (a) glass; (b) SiO2/glass; (c) Si.
Figure 7
Figure 7
RMS roughness of ITO films before and after Zn doping, as a function of the substrate used: glass, SiO2/glass, and Si.
Figure 8
Figure 8
Optical constants—n, k (a–f), thickness—d (g), optical band gap—Eg (h), porosity—P (i), and transmission—T (j,k) resulting from ellipsometric measurements and analysis of undoped and doped ITO thin films.
Figure 8
Figure 8
Optical constants—n, k (a–f), thickness—d (g), optical band gap—Eg (h), porosity—P (i), and transmission—T (j,k) resulting from ellipsometric measurements and analysis of undoped and doped ITO thin films.
Figure 9
Figure 9
Raman spectra of (a) ITO film on Si and (b) ITO:Zn film on Si.
Figure 10
Figure 10
Nyquist representation of the impedance plots of the ITO/Si film in air and in CO2 (1000 ppm in air) at different temperatures (100–300 °C).
Figure 11
Figure 11
Nyquist representation of the impedance plots of the ITO:Zn/Si film in air and in CO2 (1000 ppm in air) at different temperatures (100–300 °C).
Figure 12
Figure 12
Arrhenius plot of DC conductivity from impedance spectroscopy.
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References

    1. Lunt R.R., Bulovic V. Transparent, near-infrared organic photovoltaic solar cells for window and energy-scavenging applications. Appl. Phys. Lett. 2011;98:113305. doi: 10.1063/1.3567516. - DOI
    1. Tien W., Chu A. ITO distributed Bragg reflectors fabricated at low temperature for light-trapping in thin-film solar cells. Sol. Energy Mater. Sol. Cells. 2014;120:18–22. doi: 10.1016/j.solmat.2013.08.003. - DOI
    1. Taha H., Ibrahim K., Rahman M.M., Henry D.J., Yin C.Y., Veder J.P., Amri A., Zhao X., Jiang Z.T. Sol-gel derived ITO-based bi-layer and tri-layer thin film coatings for organic solar cells applications. Appl. Surf. Sci. 2020;530:147164. doi: 10.1016/j.apsusc.2020.147164. - DOI
    1. Li Z.H., Cho E.S., Kwon S.J. Laser direct patterning of the T-shaped ITO electrode for high-efficiency alternative current plasma display panels. Appl. Surf. Sci. 2010;257:776–780. doi: 10.1016/j.apsusc.2010.07.063. - DOI
    1. Vaufrey D., Ben Khalifa M., Besland M.P., Tardy J., Sandu C., Blanchin M.G., Roger J.A. Electrical and optical characteristics of indium tin oxide thin films deposited by cathodic sputtering for top emitting organic electroluminescent devices. Mater. Sci. Eng. C. 2002;21:265–271. doi: 10.1016/S0928-4931(02)00078-4. - DOI

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