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28/04/2026
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Nguyen, K. B., Tran, B. Q., La, P. P. H., & Ngo, H. D. (2026). Effect of Oxygen Concentration on the Optical and Crystal Structure of Sputtered Indium-doped ZnO thin films. Dong Thap University Journal of Science, 15(8), 1-12. https://doi.org/10.52714/dthu.ns.2674.1869
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Effect of Oxygen Concentration on the Optical and Crystal Structure of Sputtered Indium-doped ZnO thin films
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Abstract
Using RF magnetron sputtering, indium-doped ZnO (IZO) thin films were created on glass substrates, and the effects of oxygen partial pressure during deposition on the film’s optical, morphological, and structural characteristics were methodically investigated. All IZO films crystallized in a wurtzite structure with (002)-oriented by X-ray lattice planes preferentially aligned perpendicular to the substrate surface, as confirmed by X-ray diffraction. The film deposited at 10% O2 had the smallest average grain size of around 74.2 nm, according to field-emission scanning electron microscopy (FE-SEM), which showed dense and homogeneous grain. All samples had a straight band gap of about 3.4 eV, according to optical characterization using UV-Vis spectroscopy, whereas the IZO_10% O2 film had the maximum visible-light transmittance of 85%. Additionally, when the oxygen content rose, the Urbach energy dropped monotonically, suggesting a decrease in structural disorder. These results demonstrate that a critical factor controlling the microstructural development and optical performace of IZO films made by RF magnetron reactive sputtering is oxygen partial pressure.
Keywords
IZO thin film, Oxygen concentration, TCO, RF-magnetron sputtering, microstructure, optical properties
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
References
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Bhosle, V., Tiwari, A., & Narayan, J. (2006). Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO. Applied Physics Letters, 88(3).
Burstein, E. (1954). Anomalous optical absorption limit in InSb. Physical Review, 93(3), 632.
Chen, K. J., Hung, F.-Y., Chang, S.-J., & Hu, Z. S. (2009). Microstructures, optical and electrical properties of In-doped ZnO thin films prepared by sol–gel method. Applied Surface Science, 255(12), 6308–6312.
Chirakkara, S., Nanda, K. K., & Krupanidhi, S. B. (2011). Pulsed laser deposited ZnO: In as transparent conducting oxide. Thin Solid Films, 519(11), 3647–3652.
Cullity, B. D., & Smoluchowski, R. (1957). Elements of X‐ray Diffraction. Physics Today, 10(3), 50.
Feng, C., Yi-Ding, W., Da-Li, L., Jing-Zhi, Y., Bao-Jia, G., Lei, L., & Yu-Peng, A. (2009). Preparation and characterization of transparent conductive Nb-doped ZnO films by radio-frequency sputtering. Chinese Physics Letters, 26(3), 34210.
Granqvist, C. G. (2007). Transparent conductors as solar energy materials: A panoramic review. Solar Energy Materials and Solar Cells, 91(17), 1529–1598.
Hang Pham, T. K., Ngo, H. D., & Pham, H. P. (2025). Optimizing indium concentration in ZnO thin films for enhanced optical, electronic, and thermoelectric applications. Journal of Vacuum Science & Technology A, 43(5).
Hassanien, A. S., & Akl, A. A. (2016). Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films. Superlattices and Microstructures, 89, 153–169.
Kamble, S. S., Radhakrishnan, J. K., & Krishnamoorthy, R. (2018). Effect of O2 flow rate on the characteristics of ZnO thin films deposited by RF reactive magnetron sputtering. Materials Technology, 33(11), 709–715.
Khalfallah, B., Chaabouni, F., & Abaab, M. (2015). Some physical investigations on In-doped ZnO films prepared by RF magnetron sputtering using powder compacted target. Journal of Materials Science: Materials in Electronics, 26, 5209–5216.
Khranovskyy, V., Grossner, U., Nilsen, O., Lazorenko, V., Lashkarev, G. V, Svensson, B. G., & Yakimova, R. (2006). Structural and morphological properties of ZnO: Ga thin films. Thin Solid Films, 515(2), 472–476.
Kim, Y. H., Lee, K. S., Lee, T. S., Cheong, B., Seong, T.-Y., & Kim, W. M. (2009). Effects of substrate temperature and Zn addition on the properties of Al-doped ZnO films prepared by magnetron sputtering. Applied Surface Science, 255(16), 7251–7256.
Kotlyarchuk, B., Savchuk, V., & Oszwaldowski, M. (2005). Preparation of undoped and indium doped ZnO thin films by pulsed laser deposition method. Crystal Research and Technology: Journal of Experimental and Industrial Crystallography, 40(12), 1118–1123.
Lim, S. Y., Brahma, S., Liu, C.-P., Wang, R.-C., & Huang, J.-L. (2013). Effect of indium concentration on luminescence and electrical properties of indium doped ZnO nanowires. Thin Solid Films, 549, 165–171.
Luna-Arredondo, E. J., Maldonado, A., Asomoza, R., Acosta, D. R., Melendez-Lira, M. A., & Olvera, M. de la L. (2005). Indium-doped ZnO thin films deposited by the sol–gel technique. Thin Solid Films, 490(2), 132–136.
Ma, Q.-B., Ye, Z.-Z., He, H.-P., Hu, S.-H., Wang, J.-R., Zhu, L.-P., Zhang, Y.-Z., & Zhao, B.-H. (2007). Structural, electrical, and optical properties of transparent conductive ZnO: Ga films prepared by DC reactive magnetron sputtering. Journal of Crystal Growth, 304(1), 64–68.
Minami, T. (2000). New n-type transparent conducting oxides. MRS Bulletin, 25(8), 38–44.
Peng, L.-P., He, A.-L., Fang, L., & Yang, X.-F. (2022). Structure and properties of indium-doped ZnO films prepared by RF magnetron sputtering under different pressures. Rare Metals, 41(9), 3239–3243.
Peng, L. P., Fang, L., Yang, X. F., Ruan, H. B., Li, Y. J., Huang, Q. L., & Kong, C. Y. (2009). Characteristics of ZnO: In thin films prepared by RF magnetron sputtering. Physica E: Low-Dimensional Systems and Nanostructures, 41(10), 1819–1823.
Pham, A. T. T., Le, O. K. T., Van Hoang, D., Nguyen, T. H., Chen, K.-H., Park, S., Phan, T. B., & Tran, V. C. (2022). Coupling modification of Fermi level, band flattening and lattice defects to approach outstanding thermoelectric performance of ZnO films via tuning In and Ga incorporation. Acta Materialia, 241, 118415.
Pham, A. T. T., Phan, T. T. T., Nguyen, T. H., Van Hoang, D., Le, O. K. T., Doan, U. T. T., Phan, T. B., & Tran, V. C. (2023). Synergy of indium doping and hydrogenation for good-performance and high-mobility ZnO electrode films. Journal of Science: Advanced Materials and Devices, 8(3), 100569.
Pham, T. K. H., Ngo, H. D., & Pham, H. P. (2025). Enhancing Optical and Electronic Properties of Indium-doped ZnO Thin Films through Substrate Temperature Control. E-Journal of Surface Science and Nanotechnology.
Pham, T. K. H., Pham, H. P., & Ngo, H. D. (2025). Impact of Sputtering Power on Characteristics of Indium-Doped ZnO Thin Films. MATERIALS TRANSACTIONS, MT-M2025077.
Pham, T. K. H., Tran, B. Q., Nguyen, K. B., Pham, N. Y. N., Nguyen, T. H. Y., Nguyen, A. H.-T., Nguyen, N. P., Ngo, H. D., & Pham, H. P. (2025). Oxygen partial pressure effects on nickel oxide thin films and NiO/Si diode performance. Materials Advances, 6(5), 1719–1725.
Poddar, N. P., & Mukherjee, S. K. (2019). Effect of substrates and post-deposition annealing on rf-sputtered Al-doped ZnO (AZO) thin films. Journal of Materials Science: Materials in Electronics, 30(15), 14269–14280.
Radjehi, L., Djelloul, A., Lamri, S., Slim, M. F., & Rahim, M. (2019). Oxygen effect on structural and optical properties of zinc oxide. Surface Engineering, 35(6), 520–526.
Ratheesh Kumar, P. M., Kartha, C. S., & Vijayakumar, K. P. (2005). Doping of spray-pyrolyzed ZnO thin films through direct diffusion of indium: Structural optical and electrical studies. Journal of Applied Physics, 98(2).
Shaheera, M., Girija, K. G., Kaur, M., Geetha, V., Debnath, A. K., Vatsa, R. K., Muthe, K. P., & Gadkari, S. C. (2020). Characterization and device application of indium doped ZnO homojunction prepared by RF magnetron sputtering. Optical Materials, 101, 109723.
Shi, Q., Zhou, K., Dai, M., Hou, H., Lin, S., Wei, C., & Hu, F. (2013). Room temperature preparation of high performance AZO films by MF sputtering. Ceramics International, 39(2), 1135–1141.
Singh, A., Chaudhary, S., & Pandya, D. K. (2014). On the temperature dependence of mobility in hydrogenated indium-doped ZnO thin films. Acta Materialia, 77, 125–132.
Singh, A., Chaudhary, S., & Pandya, D. K. (2016). High conductivity indium doped ZnO films by metal target reactive co-sputtering. Acta Materialia, 111, 1–9.
Singh, D., Singh, S., Kumar, U., Srinivasa, R. S., & Major, S. S. (2014). Transparent conducting Ga-doped ZnO thin films grown by reactive co-sputtering of Zn and GaAs. Thin Solid Films, 555, 126–130.
Sun, H., Jen, S.-U., Chen, S.-C., Ye, S.-S., & Wang, X. (2016). The electrical stability of In-doped ZnO thin films deposited by RF sputtering. Journal of Physics D: Applied Physics, 50(4), 45102.
Zhu, H., Hüpkes, J., Bunte, E., & Huang, S. M. (2010). Oxygen influence on sputtered high rate ZnO: Al films from dual rotatable ceramic targets. Applied Surface Science, 256(14), 4601–4605.
Zhu, H., Wang, H., Wan, W., Yu, S., & Feng, X. (2014). Influence of oxygen and argon flow on properties of aluminum-doped zinc oxide thin films prepared by magnetron sputtering. Thin Solid Films, 566, 32–37.
Badadhe, S. S., & Mulla, I. S. (2009). H2S gas sensitive indium-doped ZnO thin films: Preparation and characterization. Sensors and Actuators B: Chemical, 143(1), 164–170.
Benouis, C. E., Benhaliliba, M., Juarez, A. S., Aida, M. S., Chami, F., & Yakuphanoglu, F. (2010). The effect of indium doping on structural, electrical conductivity, photoconductivity and density of states properties of ZnO films. Journal of Alloys and Compounds, 490(1–2), 62–67.
Bhosle, V., Tiwari, A., & Narayan, J. (2006). Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO. Applied Physics Letters, 88(3).
Burstein, E. (1954). Anomalous optical absorption limit in InSb. Physical Review, 93(3), 632.
Chen, K. J., Hung, F.-Y., Chang, S.-J., & Hu, Z. S. (2009). Microstructures, optical and electrical properties of In-doped ZnO thin films prepared by sol–gel method. Applied Surface Science, 255(12), 6308–6312.
Chirakkara, S., Nanda, K. K., & Krupanidhi, S. B. (2011). Pulsed laser deposited ZnO: In as transparent conducting oxide. Thin Solid Films, 519(11), 3647–3652.
Cullity, B. D., & Smoluchowski, R. (1957). Elements of X‐ray Diffraction. Physics Today, 10(3), 50.
Feng, C., Yi-Ding, W., Da-Li, L., Jing-Zhi, Y., Bao-Jia, G., Lei, L., & Yu-Peng, A. (2009). Preparation and characterization of transparent conductive Nb-doped ZnO films by radio-frequency sputtering. Chinese Physics Letters, 26(3), 34210.
Granqvist, C. G. (2007). Transparent conductors as solar energy materials: A panoramic review. Solar Energy Materials and Solar Cells, 91(17), 1529–1598.
Hang Pham, T. K., Ngo, H. D., & Pham, H. P. (2025). Optimizing indium concentration in ZnO thin films for enhanced optical, electronic, and thermoelectric applications. Journal of Vacuum Science & Technology A, 43(5).
Hassanien, A. S., & Akl, A. A. (2016). Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films. Superlattices and Microstructures, 89, 153–169.
Kamble, S. S., Radhakrishnan, J. K., & Krishnamoorthy, R. (2018). Effect of O2 flow rate on the characteristics of ZnO thin films deposited by RF reactive magnetron sputtering. Materials Technology, 33(11), 709–715.
Khalfallah, B., Chaabouni, F., & Abaab, M. (2015). Some physical investigations on In-doped ZnO films prepared by RF magnetron sputtering using powder compacted target. Journal of Materials Science: Materials in Electronics, 26, 5209–5216.
Khranovskyy, V., Grossner, U., Nilsen, O., Lazorenko, V., Lashkarev, G. V, Svensson, B. G., & Yakimova, R. (2006). Structural and morphological properties of ZnO: Ga thin films. Thin Solid Films, 515(2), 472–476.
Kim, Y. H., Lee, K. S., Lee, T. S., Cheong, B., Seong, T.-Y., & Kim, W. M. (2009). Effects of substrate temperature and Zn addition on the properties of Al-doped ZnO films prepared by magnetron sputtering. Applied Surface Science, 255(16), 7251–7256.
Kotlyarchuk, B., Savchuk, V., & Oszwaldowski, M. (2005). Preparation of undoped and indium doped ZnO thin films by pulsed laser deposition method. Crystal Research and Technology: Journal of Experimental and Industrial Crystallography, 40(12), 1118–1123.
Lim, S. Y., Brahma, S., Liu, C.-P., Wang, R.-C., & Huang, J.-L. (2013). Effect of indium concentration on luminescence and electrical properties of indium doped ZnO nanowires. Thin Solid Films, 549, 165–171.
Luna-Arredondo, E. J., Maldonado, A., Asomoza, R., Acosta, D. R., Melendez-Lira, M. A., & Olvera, M. de la L. (2005). Indium-doped ZnO thin films deposited by the sol–gel technique. Thin Solid Films, 490(2), 132–136.
Ma, Q.-B., Ye, Z.-Z., He, H.-P., Hu, S.-H., Wang, J.-R., Zhu, L.-P., Zhang, Y.-Z., & Zhao, B.-H. (2007). Structural, electrical, and optical properties of transparent conductive ZnO: Ga films prepared by DC reactive magnetron sputtering. Journal of Crystal Growth, 304(1), 64–68.
Minami, T. (2000). New n-type transparent conducting oxides. MRS Bulletin, 25(8), 38–44.
Peng, L.-P., He, A.-L., Fang, L., & Yang, X.-F. (2022). Structure and properties of indium-doped ZnO films prepared by RF magnetron sputtering under different pressures. Rare Metals, 41(9), 3239–3243.
Peng, L. P., Fang, L., Yang, X. F., Ruan, H. B., Li, Y. J., Huang, Q. L., & Kong, C. Y. (2009). Characteristics of ZnO: In thin films prepared by RF magnetron sputtering. Physica E: Low-Dimensional Systems and Nanostructures, 41(10), 1819–1823.
Pham, A. T. T., Le, O. K. T., Van Hoang, D., Nguyen, T. H., Chen, K.-H., Park, S., Phan, T. B., & Tran, V. C. (2022). Coupling modification of Fermi level, band flattening and lattice defects to approach outstanding thermoelectric performance of ZnO films via tuning In and Ga incorporation. Acta Materialia, 241, 118415.
Pham, A. T. T., Phan, T. T. T., Nguyen, T. H., Van Hoang, D., Le, O. K. T., Doan, U. T. T., Phan, T. B., & Tran, V. C. (2023). Synergy of indium doping and hydrogenation for good-performance and high-mobility ZnO electrode films. Journal of Science: Advanced Materials and Devices, 8(3), 100569.
Pham, T. K. H., Ngo, H. D., & Pham, H. P. (2025). Enhancing Optical and Electronic Properties of Indium-doped ZnO Thin Films through Substrate Temperature Control. E-Journal of Surface Science and Nanotechnology.
Pham, T. K. H., Pham, H. P., & Ngo, H. D. (2025). Impact of Sputtering Power on Characteristics of Indium-Doped ZnO Thin Films. MATERIALS TRANSACTIONS, MT-M2025077.
Pham, T. K. H., Tran, B. Q., Nguyen, K. B., Pham, N. Y. N., Nguyen, T. H. Y., Nguyen, A. H.-T., Nguyen, N. P., Ngo, H. D., & Pham, H. P. (2025). Oxygen partial pressure effects on nickel oxide thin films and NiO/Si diode performance. Materials Advances, 6(5), 1719–1725.
Poddar, N. P., & Mukherjee, S. K. (2019). Effect of substrates and post-deposition annealing on rf-sputtered Al-doped ZnO (AZO) thin films. Journal of Materials Science: Materials in Electronics, 30(15), 14269–14280.
Radjehi, L., Djelloul, A., Lamri, S., Slim, M. F., & Rahim, M. (2019). Oxygen effect on structural and optical properties of zinc oxide. Surface Engineering, 35(6), 520–526.
Ratheesh Kumar, P. M., Kartha, C. S., & Vijayakumar, K. P. (2005). Doping of spray-pyrolyzed ZnO thin films through direct diffusion of indium: Structural optical and electrical studies. Journal of Applied Physics, 98(2).
Shaheera, M., Girija, K. G., Kaur, M., Geetha, V., Debnath, A. K., Vatsa, R. K., Muthe, K. P., & Gadkari, S. C. (2020). Characterization and device application of indium doped ZnO homojunction prepared by RF magnetron sputtering. Optical Materials, 101, 109723.
Shi, Q., Zhou, K., Dai, M., Hou, H., Lin, S., Wei, C., & Hu, F. (2013). Room temperature preparation of high performance AZO films by MF sputtering. Ceramics International, 39(2), 1135–1141.
Singh, A., Chaudhary, S., & Pandya, D. K. (2014). On the temperature dependence of mobility in hydrogenated indium-doped ZnO thin films. Acta Materialia, 77, 125–132.
Singh, A., Chaudhary, S., & Pandya, D. K. (2016). High conductivity indium doped ZnO films by metal target reactive co-sputtering. Acta Materialia, 111, 1–9.
Singh, D., Singh, S., Kumar, U., Srinivasa, R. S., & Major, S. S. (2014). Transparent conducting Ga-doped ZnO thin films grown by reactive co-sputtering of Zn and GaAs. Thin Solid Films, 555, 126–130.
Sun, H., Jen, S.-U., Chen, S.-C., Ye, S.-S., & Wang, X. (2016). The electrical stability of In-doped ZnO thin films deposited by RF sputtering. Journal of Physics D: Applied Physics, 50(4), 45102.
Zhu, H., Hüpkes, J., Bunte, E., & Huang, S. M. (2010). Oxygen influence on sputtered high rate ZnO: Al films from dual rotatable ceramic targets. Applied Surface Science, 256(14), 4601–4605.
Zhu, H., Wang, H., Wan, W., Yu, S., & Feng, X. (2014). Influence of oxygen and argon flow on properties of aluminum-doped zinc oxide thin films prepared by magnetron sputtering. Thin Solid Films, 566, 32–37.
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