Theoretical and Experimental Comparison of the Properties of Hexagonal Wurtzite ZnO

Year 2025, Volume: 15 Issue: 4, 1329 - 1342

Zafer Gültekin

https://doi.org/10.21597/jist.1706353

Abstract

In this study, the optical and electronic properties of ZnO thin films were systematically investigated using both experimental methods and density functional theory (DFT) calculations. Structural optimizations and electrofilmnic property analyses were conducted using the PBE exchange–correlation functional. The results confirm that ZnO is a direct band gap semiconductor; however, the theoretically calculated band gap (0.87 eV) was significantly lower than the experimentally determined value (3.40 eV), consistent with the well-known underestimation problem of conventional DFT. This highlights the necessity of employing advanced computational methods such as hybrid functionals or GW corrections for precise band gap estimations. Despite the numerical discrepancy in band gap values, a strong spectral agreement was observed between the theoretical and experimental optical parameters, including the absorption coefficient, extinction coefficient, refractive index, and dielectric constants. Both methods indicated prominent optical transitions around 3.2–3.4 eV, especially in the UV region. Additionally, XRD and SEM analyses revealed high crystallinity and a homogeneous nanostructured morphology.

Keywords

DFT , Metal-oxide thin films , Spin coating , Sol-Gel

Hegzagonal Wurtzite ZnO'nun Özelliklerinin Teorik ve Deneysel Karşılaştırması

Abstract

Bu çalışmada, ZnO ince filmlerin optik ve elektronik özellikleri hem deneysel yöntemler hem de yoğunluk fonksiyonel teorisi (DFT) hesaplamaları kullanılarak sistematik olarak araştırılmıştır. Yapısal optimizasyonlar ve elektronik özellik analizleri, PBE değişim–korelasyon fonksiyonu kullanılarak gerçekleştirilmiştir. Sonuçlar, ZnO'nun doğrudan bant aralığına sahip bir yarıiletken olduğunu doğrulamaktadır; ancak teorik olarak hesaplanan bant aralığı değeri (0.87 eV), deneysel olarak belirlenen değerin (3.40 eV) oldukça altında kalmıştır. Bu durum, geleneksel DFT yöntemlerinin bant aralığını küçümseme eğilimine sahip olduğu yönündeki genel kabul ile uyumludur. Bu da, bant aralığının daha doğru tahmin edilebilmesi için hibrit fonksiyoneller veya GW düzeltmeleri gibi ileri düzey hesaplama yöntemlerinin gerekliliğini ortaya koymaktadır. Sayısal bant aralığı farkına rağmen, teorik ve deneysel optik parametreler arasında — soğurma katsayısı, sönümleme katsayısı, kırılma indisi ve dielektrik sabitleri dahil olmak üzere — güçlü bir spektral uyum gözlemlenmiştir. Her iki yöntem de özellikle UV bölgesinde, 3.2–3.4 eV civarında belirgin optik geçişleri göstermiştir. Ayrıca, XRD ve SEM analizleri, yüksek kristallilik ve homojen nanoyapılı bir morfolojiyi ortaya koymuştur.

Keywords

DFT , Metal-oksit ince filmler , Spin kaplama , Sol-Jel

References

• Agarwal, S., Jangir, L. K., Rathore, K. S., Kumar, M., & Awasthi, K. (2019). Morphology-dependent structural and optical properties of ZnO nanostructures. Applied Physics A, 125(8), 553.
• Al-Ariki, S., Yahya, N. A., Al-A’nsi, S. A. A., Jumali, M. H., Jannah, A. N., & Abd-Shukor, R. (2021). Synthesis and comparative study on the structural and optical properties of ZnO doped with Ni and Ag nanopowders fabricated by sol gel technique. Scientific Reports, 11(1), 11948.
• Alsaad, A. M., Al-Bataineh, Q. M., Ahmad, A. A., Albataineh, Z., & Telfah, A. (2020). Optical band gap and refractive index dispersion parameters of boron-doped ZnO thin films: A novel derived mathematical model from the experimental transmission spectra. Optik, 211, 164641.
• Amakali, T., Daniel, L. S., Uahengo, V., Dzade, N. Y., & De Leeuw, N. H. (2020). Structural and optical properties of ZnO thin films prepared by molecular precursor and sol–gel methods. Crystals, 10(2), 132.
• Alharshan, G. A., Aboraia, A. M., Uosif, M. A., Sharaf, I. M., Shaaban, E. R., Saad, M., ... & Elsenety, M. M. (2023). Optical band gap tuning, DFT understandings, and photocatalysis performance of ZnO nanoparticle-doped Fe compounds. Materials, 16(7), 2676.
• Ayana, A., Gummagol, N. B., Patil, P. S., Sharma, P., & Rajendra, B. V. (2024). Nonlinear optical properties of zinc oxide thin films. Optics & Laser Technology, 175, 110820.
• Baizid, A., Mokadem, A., Ouerdane, A., Guezzoul, M. H., Bouslama, M. H., Benchenane, H., ... & Halati, M. S. (2021). First principles calculation of structural, electronic and optical properties of K-doped ZnO. Computational Condensed Matter, 27, e00558.
• Bashyal, K., Pyles, C. K., Afroosheh, S., Lamichhane, A., & Zayak, A. T. (2018). Empirical optimization of DFT+ U and HSE for the band structure of ZnO. Journal of Physics: Condensed Matter, 30(6), 065501.
• Benkrima, Y., Benhamida, S., & Belfennache, D. (2023). Theoretical study of structural and optical properties of ZnO in wurtzite phase. Digest Journal of Nanomaterials & Biostructures (DJNB), 18(1).
• Boruah, B. D. (2019). Zinc oxide ultraviolet photodetectors: rapid progress from conventional to self-powered photodetectors. Nanoscale Advances, 1(6), 2059-2085.
• Darma, Y., Setiawan, F. G., Majidi, M. A., & Rusydi, A. (2015). Theoretical investigation on electronic properties of ZnO crystals using DFT-based calculation method. Advanced Materials Research, 1112, 41-44.
• Dubey, K. C., Zaidi, A., & Awasthi, R. R. (2022). Environmentally benign structural, topographic, and sensing properties of pure and Al-doped ZnO thin films. ACS omega, 7(33), 28946-28954.
• Dutta, M., Mridha, S., & Basak, D. (2008). Effect of sol concentration on the properties of ZnO thin films prepared by sol–gel technique. Applied Surface Science, 254(9), 2743-2747.
• El Hallani, G., Khuili, M., Fazouan, N., Liba, A., Abou El Makarim, H., & Atmani, E. H. (2024). Experimental and DFT investigations of Al-doped ZnO nanostructured thin films. Chemical Physics Impact, 8, 100648.
• Gültekin, Z., Alper, M., Hacıismailoğlu, M. C., & Akay, C. (2023). Effect of Mn doping on structural, optical and magnetic properties of ZnO films fabricated by sol–gel spin coating method. Journal of Materials Science: Materials in Electronics, 34(5), 438.
• Gültekin, Z., Akay, C., & Altınölçek, N. (2024). Investigation of Spintronic Properties of Transition Metal Doped ZnO Thin Films Produced by Sol-Gel Spin Coating. Sakarya University Journal of Science, 28(5), 1047-1058.
• Haffad, S., Cicero, G., & Samah, M. (2011). Structural and electronic properties of ZnO nanowires: a theoretical study. Energy Procedia, 10, 128-137.
• Hasan, B. A. (2021, March). Investigating the Effect of ZnO on the Structural and Optical Properties of (MgO)1-x (ZnO)x via Pulsed Laser Deposition. In Journal of Physics: Conference Series (Vol. 1829, No. 1, p. 012032). IOP Publishing.
• Hasnidawani, J. N., Azlina, H. N., Norita, H., Bonnia, N. N., Ratim, S., & Ali, E. S. (2016). Synthesis of ZnO nanostructures using sol-gel method. Procedia chemistry, 19, 211-216.
• Ilickas, M., Marčinskas, M., Peckus, D., Mardosaitė, R., Abakevičienė, B., Tamulevičius, T., & Račkauskas, S. (2023). ZnO UV sensor photoresponse enhancement by coating method optimization. Journal of Photochemistry and Photobiology, 14, 100171.
• Janotti, A., & Van de Walle, C. G. (2009). Fundamentals of zinc oxide as a semiconductor. Reports on progress in physics, 72(12), 126501.
• Jongnavakit, P., Amornpitoksuk, P., Suwanboon, S., & Ratana, T. (2012). Surface and photocatalytic properties of ZnO thin film prepared by sol–gel method. Thin Solid Films, 520(17), 5561-5567.
• Kaushik, V., Bhardwaj, K., Kumar, D., Kumar, M., & Sharma, S. K. (2024). Effect of various processing parameters on the properties of ZnO thin films. Hybrid Advances, 7, 100295.
• Kholtobina, A. S., Kovaleva, E. A., Melchakova, J., Ovchinnikov, S. G., & Kuzubov, A. A. (2021). Theoretical investigation of the prospect to tailor ZnO electronic properties with VP thin films. Nanomaterials, 11(6), 1412.
• Krysova, H., Mansfeldova, V., Tarabkova, H., Pisarikova, A., Hubicka, Z., & Kavan, L. (2024). High-quality dense ZnO thin films: work function and photo/electrochemical properties. Journal of Solid State Electrochemistry, 28(8), 2531-2546.
• Mohamad, A. A., Hassan, M. S., Yaakob, M. K., Taib, M. F. M., Badrudin, F. W., Hassan, O. H., & Yahya, M. Z. A. (2017). First-principles calculation on electronic properties of zinc oxide by zinc–air system. Journal of King Saud University-Engineering Sciences, 29(3), 278-283.
• Muchuweni, E., Sathiaraj, T. S., & Nyakotyo, H. (2017). Synthesis and characterization of zinc oxide thin films for optoelectronic applications. Heliyon, 3(4).
• Muslih, E. Y., & Kim, K. H. (2017, July). Preparation of zinc oxide (ZnO) thin film as transparent conductive oxide (TCO) from zinc complex compound on thin film solar cells: A study of O2 effect on annealing process. In IOP Conference Series: Materials Science and Engineering (Vol. 214, No. 1, p. 012001). IOP Publishing.
• Ouni, B., Larbi, T., & Amlouk, M. (2022). Vibrational, Electronic and Structural Study of Sprayed ZnO Thin Film Based on the IR-Raman Spectra and DFT Calculations. Crystal Structure Theory and Applications, 11(2), 23-38.
• Otieno, F., Airo, M., Erasmus, R. M., Billing, D. G., Quandt, A., & Wamwangi, D. (2018). Effect of thermal treatment on ZnO:Tb3+ nano-crystalline thin films and application for spectral conversion in inverted organic solar cells. RSC advances, 8(51), 29274-29282.
• Pearton, S. J., & Ren, F. (2014). Advances in ZnO-based materials for light emitting diodes. Current Opinion in Chemical Engineering, 3, 51-55.
• Safeen, K., Safeen, A., Arif, D., Shah, W. H., Ali, A., Ali, G., & Ahmad, K. S. (2023). Tuning the optical properties of ZnO by Co and Gd doping for water pollutant elimination. Water, 15(8), 1470.
• Schleife, A., Fuchs, F., Furthmüller, J., & Bechstedt, F. (2006). First-principles study of ground-and excited-state properties of MgO, ZnO, and CdO polymorphs. Physical Review B-Condensed Matter and Materials Physics, 73(24), 245212.
• Shokri, A., Yazdani, A., & Rahimi, K. (2020). Possible bandgap values of graphene-like ZnO in density functional theory corrected by the Hubbard U term and HSE hybrid functional. Materials Today Communications, 22, 100756.
• Toma, F. T. Z., Rahman, M. S., & Maria, K. H. (2025). A review of recent advances in ZnO nanostructured thin films by various deposition techniques. Discover Materials, 5(1), 60.
• Uribe-López, M. C., Hidalgo-López, M. C., López-González, R., Frías-Márquez, D. M., Núñez-Nogueira, G., Hernández-Castillo, D., & Alvarez-Lemus, M. A. (2021). Photocatalytic activity of ZnO nanoparticles and the role of the synthesis method on their physical and chemical properties. Journal of Photochemistry and photobiology A: Chemistry, 404, 112866.
• Wibowo, A., Marsudi, M. A., Amal, M. I., Ananda, M. B., Stephanie, R., Ardy, H., & Diguna, L. J. (2020). ZnO nanostructured materials for emerging solar cell applications. RSC advances, 10(70), 42838-42859.