Structural Investigation of ZnO Thin Films Obtained by Annealing after Thermal Evaporation

In this study, ZnO thin films, with thicknesses of 80-240 nm are prepared by thermal evaporation of ZnO pellets on glass substrates. Then, these films are annealed in air atmosphere at 300C for 2 hours. ZnO formation has been investigated as a function of the film thickness. As deposited films appear to be brown since they are rich in Zn, whereas Zn phases are replaced by ZnO phases after annealing and the films show a transparent appearance. In thinner films (80-100 nm) the ZnO phases are not observed, but Zn phase intensities decrease after annealing. Especially when the thickness is increased in 132-240 nm thick films, ZnO phases are observed after annealing, and their intensity is increased and polycrystalline structures are formed. XRD measurements show that Zn (002), Zn (100) and Zn (101) phases are present in our films before annealing. After annealing, the intensity of these zinc peaks decreases firstly due to the film thickness, and then at ZnO (100), ZnO (002) and ZnO (101) phases are formed. SEM, AFM analyzes show that ZnOs are formed in the form of nanorods on the surface and after these anneal the columnar growths occur and the particle diameters increase.

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A. Zaier, A. Meftah, A. Y. Jaber, A. A. Abdelaziz, M. S. Aida, “Annealing effects on the structural, electrical and optical properties of ZnO thin films prepared by thermal evaporation technique”, Journal of King Saud University Science, vol. 27, no.4, pp. 356-360, 2015.

P. Rai, R. Khan, R. Ahmad, Y. B. Hahn, I. H. Lee, Y. T. Yu, “Gas sensing properties of single crystalline ZnO nanowires grown by thermal evaporation technique”, Current Applied Physics, vol 13 no.8, pp 1769-1773, 2013

S. Singh, P. Chakrabarti, “Comparison of the structural and optical properties of ZnO thin films deposited by three different methods for optoelectronic applications” Superlattices and Microstructures, vol.64, pp.283-293, 2013.

N. K. Park, Y Lee, S Yoon, G Han, S Ryu, T Lee, W Lee, and Y Bae, “The Epitaxial Growth of ZnO Nanowires for Optical Devices by a Modified Thermal Evaporation Method”, Scripta Materialia, vol.59, no.3, pp.328–31, 2008.

N. E. Duygulu, A. O. Kodolbas and A. Ekerim, “Influence of Deposition Parameters on ZnO and ZnO:Al Thin Films”, Physica Status Solidi(C), vol.11 pp.1460–63, 2014.

Chongsri, K., and W. Pecharapa, “UV Photodetector Based on Al-Doped ZnO Nanocrystalline Sol-Gel Derived Thin Fims”, Energy Procedia, vol.56, pp.554– 559, 2014.

Ü. Özgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Doğan, V. Avrutin, S.-J. Cho, and H. Morkoç, “A Comprehensive Review of ZnO Materials and Devices”, Journal of Applied Physics, vol.98, pp.041301-102, 2005.

L. Schmidt-Mende, J. L.MacManus-Driscoll, “ZnO–nanostructures, defects, and devices”, Materials Today, vol.10, no.5, pp.40-48, 2007.

R. Mariappan, V. Ponnuswamy, P. Suresh, N. Ashok, P. Jayamurugan, and A. Chandra Bose, “Influence of Film Thickness on the Properties of Sprayed ZnO Thin Films for Gas Sensor Applications”, Superlattices and Microstructures, vol.71, pp.238-249, 2014.

Rusli, Nurul Izni, Masahiro Tanikawa, Mohamad Rusop Mahmood, Kanji Yasui, and Abdul Manaf Hashim, “Growth of High- Density Zinc Oxide Nanorods on Porous Silicon by Thermal Evaporation”, Materials, vol.5, pp.2817–2832, 2012.

N.Bouhssira, S. Abed, E. Tomasella, J.Cellier, A. Mosbah, M. S. Aida, M. Jacquet,“Influence of annealing temperature on the properties of ZnO thin films deposited by thermal evaporation”, Applied Surface Science, vol. 252, pp.5594-5597, 2006.

A.Ghaderi, S. M. Elahi, S. Solaymani, M. Naseri, M. Ahmadirad, S. Bahrami, A. E. Khalili, “Thickness dependence of the structural and electrical properties of ZnO thermal-evaporated thin films”, Pramana, vol.77, no.6, 1171-1178, 2011.