Tuning the Band Gap of ZnO Thin Films by Mg Doping

Abstract:

Structural, morphological, optical and electrical properties of magnesium (Mg) doped zinc oxide (ZnO) films prepared by ultrasonic spray pyrolysis technique on microscope glass substrate, have been studied in terms of Mg doping content. The precursors solutions of Mg doped ZnO films were prepared from zinc acetate dihydrate (Zn (CH₃OO)₂⋅2H₂O) and magnesium acetate tetrahydrate (CH₃COO)₂Mg⋅4H₂O) acted as dopant. The compositions of these solutions were fixed at 0.02 M of Zn (CH₃OO)₂.2H₂O and the atomic percentage ratio of Mg/Zn was varied from 0 to 20 atomic %. The XRD pattern of all films showed ZnO hexagonal wurtzite structure and the morphology showed homogeneous structure/texture and pinhole-free with adding Mg content. It was found that Mg²⁺ ions do not change conductivity of ZnO films due to the partial substitution of Zn²⁺ ion by the same valence Mg²⁺ ion. For optical properties, all films showed high transmittance over 80% and absorbance about 0.01 in visible and near infrared regions. Moreover, the Mg dopant affects on a shift of the absorption edge in transmittance spectra of the films to a lower wavelength in ultraviolet region and increases the band gap of the samples.

• Periodical: Key Engineering Materials (Volume 690)
• Pages: 131-136
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.690.131
• Online since: May 2016
• Authors: Sutatip Thonglem, Chavalit Suksri, Kamonpan Pengpat, Gobwute Rujijanagul, Sukum Eitssayeam, Uraiwan Intatha, Tawee Tunkasiri*
• Keywords: Band Gap, Magnesium, Zinc Oxide

References

[1] R.M. Krishna, T.C. Hayes, D. Krementz, G. Weeks, A.M. Torres, K. Brinkman, K.C. Mandal, Characterization of transparent conducting oxide thin films deposited on ceramic substrates, Mater. Lett. 66 (2012) 233-235.

DOI: 10.1016/j.matlet.2011.08.066

[2] C. Sima, C. Grigoriu, S. Antohe, Comparison of the dye-sensitized solar cells performances based on transparent conductive ITO and FTO, Thin Solid Films. 519 (2010) 595-597.

DOI: 10.1016/j.tsf.2010.07.002

[3] S. Khodja, T. Touam, A. Chelouche, F. Boudjouan, D. Djouadi, Z. Hadjoub, A. Fischer, A. Boudrioua, Effects of stabilizer ratio on structural, morphological, optical and waveguide properties of ZnO nano-structured thin films by a sol–gel process, Superlattice. Microst. 75 (2014).

DOI: 10.1016/j.spmi.2014.08.010

[4] A. Kaushal, D. Kaur, Effect of Mg content on structural, electrical and optical properties of Zn1−xMgxO nanocomposite thin films, Mat. Sol. C. 93 (2009) 193-198.

DOI: 10.1016/j.solmat.2008.09.039

[5] S. Thonglem, S. Sirisoonthorn, K. Pengpat, G. Rujijanagul, T. Tunkasiri, U. Intatha, S. Eitssayem, Effect of Mg doping on optical properties of ZnO films by ultrasonic spray pyrolysis, Integr. Ferroelectr. 156 (2014) 153-159.

DOI: 10.1080/10584587.2014.907078

[6] S. Thonglem, S. Sirisoonthorn, K. Pengpat, G. Rujijanagul, S. Eitssayem, U. Intatha, T. Tunkasiri, Properties of Mg doped ZnO films prepared by ultrasonic spray pyrolysis, Appl. Mech. Mater. 804 (2015) 88-92.

DOI: 10.4028/www.scientific.net/amm.804.88

[7] M. Zhao, X. Wang, L. Ning, H. He, J. Jia, L. Zhang, X. Li, Synthesis and optical properties of Mg-doped ZnO nanofibers prepared by electrospinning, J. Alloys. Compd. 507 (2010) 97-100.

DOI: 10.1016/j.jallcom.2010.07.093

[8] Q. Shi, J. Zhang, D. Zhang, C, Wang, B. Yang, B. Zhang, W. Wang, Red luminescent and structural properties of Mg-doped ZnO phosphors prepared by sol–gel method, Mat. Sci. Eng. B. 177 (2012) 689-693.

DOI: 10.1016/j.mseb.2012.03.045

[9] H. Benzarouk, A. Drici, M. Mekhnache, A. Amara, M. Guerioune, J.C. Bernède, H. Bendjffal, Effect of different dopant elements (Al, Mg and Ni) on microstructural, optical and electrochemical properties of ZnO thin films deposited by spray pyrolysis (SP), Superlat. Microst. 52 (2012).

DOI: 10.1016/j.spmi.2012.06.007

[10] C.E. Benouis, M. Benhaliliba, F. Yakuphanoglu, A.T. Silver, M.S. Aida, A.S. Juarez, Physical properties of ultrasonic sprayed nanosized indium doped SnO2 films, Synthetic. Met. 161 (2011) 1509-1516.

DOI: 10.1016/j.synthmet.2011.04.017

[11] I. Volintiru, M. Creatore, B. J. Kniknie, C. I. M. A. Spee, M. C. M. van de Sanden, Evolution of the electrical and structural properties during the growth of Al doped ZnO films by remote plasma-enhanced metalorganic chemical vapor deposition, J. Appl. Phys. 102 (2007).

DOI: 10.1063/1.2772569

[12] K. Huang, Z. Tang, L. Zhang, J. Yu, J. Lv, X. Liu, F. Liu, Preparation and characterization of Mg-doped ZnO thin films by sol–gel method, Appl. Surf. Sci. 258 (2012) 3710-3713.

DOI: 10.1016/j.apsusc.2011.12.011

[13] S. Thonglem, U. Intatha, S. Eitssayeam, Effect of magnesium and fluorine dopants on properties of ZnO thin films, Ceram. Int. 41 (2015) S331-S336.

DOI: 10.1016/j.ceramint.2015.03.215

[14] R. Ding, C. Xu, B. Gu, Z. Shi, H. Wang, L. Ba, Z. Xiao, Effect of Mg incorporation on microstructure and optical properties of ZnO thinf gilms prepared by sol-gel method, J. Mater. Sci. Technol. 26(7) (2010), 601-604.

DOI: 10.1016/s1005-0302(10)60092-8

[15] J. Yang, Y. Wang, J. Kong, M. Yu, H. Jin, Synthesis of Mg-doped hierarchical ZnO nanostructures via hydrothermal method and their optical properties, J. Alloys. Compd. 657 (2016) 261-267.

DOI: 10.1016/j.jallcom.2015.10.117

[16] C.A. Hoel, T.O. Mason, J-F. Gaillard, K.R. Poeppelmeier, Transparent Conducting Oxides in the ZnO-In2O3-SnO2 System, Chem. Mater. 22 (2010) 3569-3579.

DOI: 10.1002/chin.201034222