Influence of Al content on microstructure and optical transmittance of sol-gel dip-coated ZnO films

  • Mehdi Tonka 1
  • Feyza Guzelcimen 2
  • Nilgun Baydogan 3
  • 1 Department of Optician, Vocational School of Health Care, Sirnak University, Sirnak, Türkiye
  • 2 Physics Department, Science Faculty, Istanbul University, Istanbul, Türkiye
  • 3 Energy Institute, Istanbul Technical University, Ayazaga Campus, Istanbul, Türkiye


Aluminum-doped zinc oxide thin film (Al:ZnO) was derived by the sol-gel dip-coating technique to analyze the doping effect on the film’s crystal structure and optical transparency. The surface structure of the thin film had the particles in the nano-spherical form. Al amount changed surface roughness with the variation of the grain size. The crystal structure of ZnO was wurtzite (in XRD analysis). The surface morphology of the film was also examined with SEM images. The effect of Al doping was investigated to evaluate the necessary amount of Al on the optical properties. The films show high optical transparency (~85%) at specific Al doping amounts (0.8–1.6%).


Download data is not yet available.
Keywords: Crystallinity, Sol-gel, Transparency, Optical properties, ZnO


[1] T. Saidani, M. Zaabat, M.S. Aida, B. Boudine, Efect of copper doping on the photocatalytic activity of ZnO thin flms prepared by sol-gel method, Superlattices Microstruct. 88 (2015) 315–322.
[2] R. Tena-Zaera, J. Elias, C. Lévy-Clément, ZnO nanowire arrays: Optical scattering and sensitization to solar light, Appl. Phys. Lett. 93 (2008) 233119.
[3] H. Fan, Z. Yao, C. Xu, X. Wang, Z. Yu, Effects of Na Doping on Structural, Optical, and Electronic Properties of ZnO Thin Films Fabricated by Sol–Gel Technique, J. Electron. Mater. 47 (2018) 3847–3854.
[4] N. Saito, H. Haneda, T. Sekiguchi, N. Ohashi, I. Sakaguchi, K. Koumoto, Low-Temperature Fabrication of Light-Emitting Zinc Oxide Micropatterns Using Self-Assembled Monolayers, Adv. Mater. 14 (2002) 418–421.<418::AID-ADMA418>3.0.CO;2-K.
[5] M. Hjiri, L. El Mir, S.G. Leonardi, A. Pistone, L. Mavilia, G. Neric, Al-doped ZnO for highly sensitive CO gas sensors, Sens. Actuators B: Chem. 196 (2014) 413–420.
[6] S. Fujihara, C. Sasaki, T. Kimura, Crystallization behavior and origin of c-axis orientation in sol–gel derived ZnO:Li thin films on glass substrates, Appl. Surf. Sci. 180 (2001) 341–350.
[7] M. Ohyama, H. Kozuka, T. Yoko, Sol-gel preparation of ZnO films with extremely preferred orientation along (002) plane from zinc acetate solution, Thin Solid Films. 306 (1997) 78–85.
[8] C. Philibert, The present and future use of solar thermal energy as a primary source of energy, International Energy Agency, Paris. (2005) 1–16.
[9] J.F. Chang, H.H. Kuo, I.C. Leu, M.H. Hon, The effects of thickness and operation temperature on ZnO: Al thin film CO gas sensor, Sens. Actuators B: Chem. 84 (2002) 258–264.
[10] O. Urper, N. Baydogan, Influence of structural changes on electrical properties of Al:ZnO films, Mater. Lett. 258 (2020) 126641.
[11] O. Urper, N. Baydogan, Effect of Al concentration on optical parameters of ZnO thin film derived by Sol-Gel dip coating technique, Mater. Lett. 274 (2020) 128000.
[12] M. Hou, Z. Zhou, A. Xu, K. Xiao, J. Li, et al., Synthesis of group II-VI semiconductor nanocrystals via phosphine free method and their application in solution processed photovoltaic devices, Nanomaterials. 11 (2021) 2071.
[13] M. Ohyama, H. Kozuka, T. Yoko, Sol-Gel Preparation of Transparent and Conductive Aluminum-Doped Zinc Oxide Films with Highly Preferential Crystal Orientation, J. Am. Ceram. Soc. 81 (1998) 1622.
[14] D. Bao, H. Gu, A. Kuang, Sol-gel-derived c-axis oriented ZnO thin films, Thin Solid Films. 312 (1998) 37–39.
[15] J.F. Chang, W.C. Lin, M.H. Hon, Effects of post-annealing on the structure and properties of Al-doped zinc oxide films, Appl. Surf. Sci. 183 (2001) 18–25.
[16] E. Fortunato, P. Nunes, A. Marques, D. Costa, H. Aguas, et al., Influence of the Strain on the Electrical Resistance of Zinc Oxide Doped Thin Film Deposited on Polymer Substrates, Adv. Eng. Mater. 4 (2002) 610–612.<610::AID-ADEM610>3.0.CO;2-1.
[17] S. Bandyopadhyay, G.K. Paul, S.K. Sen, Study of optical properties of some sol–gel derived films of ZnO, Sol. Energy Mater. Sol. Cells. 71 (2002) 103–113.
[18] J.G. Lu, Y.Z. Zhang, Z.Z. Ye, Y.J. Zeng, H.P. He, et al., Control of ????- and ????-type conductivities in Li-doped ZnO thin films, Appl. Phys. Lett. 89 (2006) 112113.
[19] S.J. Jiao, Y.M. Lu, D.Z. Shen, Z.Z. Zhang, B.H. Li, et al., Donor–acceptor pair luminescence of nitrogen doping p-type ZnO by plasma-assisted molecular beam epitaxy, J. Lumin. 122 (2007) 368–370.
[20] C. Wang, Z. Ji, J. Xi, J. Du, Z. Ye, Fabrication and characteristics of the low-resistive p-type ZnO thin films by DC reactive magnetron sputtering, Mater. Lett. 60 (2006) 912–914.
[21] L. Znaidi, T. Chauveau, A. Tallaire, F. Liu, M. Rahmani, et al., Textured ZnO thin films by sol–gel process: Synthesis and characterizations, Thin Solid Films. 617 (2016) 156–160.
[22] D.J. Winarski, W. Anwand, A. Wagner, P. Saadatkia, F.A. Selim, et al., Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies, AIP Adv. 6 (2016) 4962658.
[23] L. Znaidi, T. Touam, D. Vrel, N. Souded, S.B. Yahia, et al., AZO thin films by sol-gel Process for Integrated Optics, Coatings. 3 (2013) 126–139.
[24] Z. Zhou, K. Kato, T. Komaki, M. Yoshino, H. Yukawa, M. Morinaga, Effects of hydrogen doping through ion implantation on the electrical conductivity of ZnO, Int. J. Hydrog. Energy. 29 (2004) 323–327.
[25] R. Swanepoel, Determination of the thickness and optical constants of amorphous silicon, J. Phys. E: Sci. Instrum. 16 (1983) 1214.
[26] B.D. Cullity, S.R. Stock, Elements of X-ray diffraction, 3rd Edition, Prentice-Hall, New York. (2001).
[27] C. Guillen, J. Herrero, Optical, electrical and structural characteristics of Al:ZnO thin films with various thicknesses deposited by DC sputtering at room temperature and annealed in air or vacuum, Vacuum. 84 (2010) 924–929.
[28] N. Baydogan, O. Karacasu, H. Cimenoglu, ZnO:Al thin films used in ZnO: Al/p-Si heterojunctions, J. Sol-Gel Sci. Technol. 61 (2012) 620–627.
[29] N. Baydogan, O. Karacasu, H. Cimenoglu, Effect of annealing temperature on ZnO:Al/p-Si heterojunctions, Thin Solid Films. 520 (2012) 5790–5796.
[30] P. Shafiee, M. Reisi Nafchi, S. Eskandarinezhad, S. Mahmoudi, E. Ahmadi, Sol-gel zinc oxide nanoparticles: advances in synthesis and applications, Synth. Sinter. 1 (2021) 242–254.

Cited By

Crossref Google Scholar
Influence of Al content on microstructure and optical transmittance of sol-gel dip-coated ZnO films
How to Cite
Tonka, M., Guzelcimen, F., & Baydogan, N. (2022). Influence of Al content on microstructure and optical transmittance of sol-gel dip-coated ZnO films. Synthesis and Sintering, 2(3), 105-109.