Effect of Annealing Temperature on Structural and Optical Properties of Sol-Gel-Derived ZnO Thin Films


Nanocrystalline ZnO thin films were deposited on glass substrate via sol-gel dip-coating technique then annealed at 300A degrees C, 400A degrees C, and 500A degrees C for 1 h. Their optical, structural, and morphological properties were studied using ultraviolet-visible (UV-Vis) spectrophotometry, x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). XRD diffraction revealed that the crystalline nature of the thin films increased with increasing annealing temperature. The c-axis orientation improved, and the grain size increased, as indicated by increased intensity of the (002) plane peak at 2 theta = 34.42A degrees corresponding to hexagonal ZnO crystal. The average crystallite size of the thin films ranged from 13 nm to 23 nm. Increasing the annealing temperature resulted in larger crystallite size and higher crystallinity with increased surface roughness. The grain size according to SEM analysis was in good agreement with the x-ray diffraction data. The optical bandgap of the thin films narrowed with increasing annealing temperature, lying in the range of 3.14 eV to 3.02 eV. The transmission of the thin films was as high as 94% within the visible region. The thickness of the thin films was 400 nm, as measured by ellipsometry, after annealing at the different temperatures of 300A degrees C, 400A degrees C, and 500A degrees C.



subject category

Engineering; Materials Science; Physics


Arif, M; Sanger, A; Vilarinho, PM; Singh, A

our authors


The authors are grateful to Department of Science and Technology Ministry of Science and Technology & University Grants Commission, Government of India for the financial support. A.S. would like to thank the Department of Science & Technology, Ministry of Science & Technology, Govt. of India for the award of BOYCAST Fellowship. M.A. would like to express sincere gratitude to Prof. Talat Ahmad, Vice Chancellor, Jamia Millia Islamia University for the valuable encouragement and his active extended support in pursuance of my research work.

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