Effect of Sr Content on Microstructure and Electrical Properties of Lead-free Ba1-xSrxTiO3 thin Films
Main Article Content
Abstract
Lead-free barium titanate based Ba1-xSrxTiO3 thin films (x = 0 ÷ 0.45) have been deposited onto Pt/Ti/SiO2/Si(100) substrate via sol–gel technique. The films were crystallized at temperature of 650 °C for 30 min in the air. The experimental data displayed that microstructure, dielectric and ferroelectric properties of the films were strongly influenced by the Sr concentration. All the films are well formed in a polycrystalline perovskite phase with a shift of diffraction planes toward larger 2θ as increasing Sr content. High resolution scanning electron microscopy images as well as cross-section profile indicate a dense structure, clear grains and a sharp interface between the film and Pt electrode. However, the shape and grain size change among Sr-doped films. Series data on capacitance ˗ voltage measurements reveal that dielectric constant (ε) increases with Sr-dopant concentration while loss tangent (tanδ) decreases. The optimal dielectric properties are found for Ba0.55Sr0.45TiO3 (x= 0.45), while Ba0.65Sr0.35TiO3 (x= 0.35) thin films perform better polarization properties with the maximum polarization of 8.07 mC/cm2 under applied electric field of 1,000 kV/cm.
Keywords:
Lead-free BST-BZT thin film, chemical solution deposition, microstructure, dielectrics.
References
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[2] T. H. E. E. Parliament, T. H. E. Council, O. F. The, E. Union, Restriction of The Use of Certain Hazardous Substances in Electrical and Electronic Equipment (RoHS), Official Journal European Union, Vol. 54, 2011,
pp. L174/88-L174/110, https://doi.org/10.3000/17252555.L_2011.174.eng.
[3] P. Bao, T. J. Jackson, X. Wang, M. J. Lancaster, Barium Strontium Titanate Thin Film Varactors for Room-Temperature Microwave Device Applications, Journal Physics D: Applied Physics, Vol. 41, No. 6, 2008,
pp. 063001–063021, https://doi.org/10.1088/0022-3727/41/6/063001.
[4] A. Khalfallaoui, G. Velu, L. Burgnies, J. C. Carru, Characterization of Doped BST Thin Films Deposited by Sol-gel for Tunable Microwave Devices, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol. 57, 2009, pp. 295-298, https://doi.org/10.1109/FREQ.2009.5168189.
[5] S. U. Adikary, H. L. W. Chan, Compositionally Graded BaxSr1-xTiO3 Thin Films for Tunable Microwave Applications, Material Chemistry Physics, Vol. 79, No. 2–3, 2003, pp. 157-160, https://doi.org/10.1016/S0254-0584(02)00255-9.
[6] V. Polinger, I. B. Bersuker, Pseudo Jahn-Teller Effect in Permittivity of Ferroelectric Perovskites, Journal of Physics Conference Series, Vol. 833, 2017, pp. 012012, https://doi.org/10.1088/1742-6596/833/1/012012.
[7] A. Debnath, S. K. Lalwani, S. Singh, Sunny, Improvement in Ferroelectric Properties of BaTiO3 Film by Mn/Sr Doping for Non-volatile Memory Applications, Micro and Nanostructures, Vol. 171, 2022, pp. 207421, https://doi.org/10.1016/j.micrna.2022.207421.
[8] S. W. Kim, H. I. Choi, M. H. Lee, J. S. Park, D. J. Kim, D. Do, M. H. Kim, T. K. Song, W. J. Kim, Electrical Properties and Phase of BaTiO3-SrTiO3 Solid Solution, Ceramics International, Vol. 39, 2013, pp. S487-S490, https://doi.org/10.1016/j.ceramint.2012.10.119.
[9] Y. Yu, H. Zou, Q. F. Cao, X. S. Wang, Y. X. Li, X. Yao, Phase Transitions and Relaxation Behaviors in Barium Strontium Titanate Ceramics Determined by Dynamic Mechanical and Dielectric Analysis, Ferroelectrics,
Vol. 487, 2015, pp. 77-85, https://doi.org/10.1080/00150193.2015.1070641.
[10] L. C. Sengupta, S. Sengupta, Breakthrough Advances in Low Loss, Tunable Dielectric Materials, Material Research Innovations, Vol. 2, 1999, pp. 278-282, https://doi.org/10.1007/s100190050098.
[11] C. S. G. Derived, M. C. Gust, L. A. Momoda, N. D. Evans, M. L. Mecartney, Crystallization of Sol–Gel-Derived Barium Strontium Titanate Thin Films, Journal American Ceramic Society, Vol. 92, 2001, pp. 1087–1092, https://doi.org/10.1111/j.1151-2916.2001.tb00794.x.
[12] N.Y. Chan, D.Y. Wang, Y. Wang, J.Y. Dai, H.L.W. Chan, The Structural and In-plane Dielectric/Ferroelectric Properties of The Epitaxial (Ba,Sr)(Zr,Ti)O3 Thin Films, Journal Applied Physics, Vol. 115, 2014, pp. 0-7, https://doi.org/10.1063/1.4883963.
[13] B. D. Stojanovic, A. Z. Simoes, C. O. Paiva-Santos, C. Jovalekic, V. V. Mitic, J. A. Varela, Mechanochemical Synthesis of Barium Titanate, Journal European Ceramic Society, Vol. 25, 2005, pp. 1985-1989, https://doi.org/10.1016/j.jeurceramsoc.2005.03.003.
[14] P. T. M. Nguyen, T. Nguyen, M. D. Nguyen, T. Vu, Impact of Electrode Materials on Microstructure, Leakage Current and Dielectric Tunable Properties of Lead-free BSZT Thin Films, Ceramics International, Vol. 47, 2021, pp. 23214-23221, https://doi.org/10.1016/j.ceramint.2021.05.033.
[15] W. C. Zhu, D. W. Peng, J. R. Cheng, Z. Y. Meng, Effect of (Ba+Sr)/Ti Ratio on Dielectric and Tunable Properties of Ba0.6Sr0.4TiO3 Thin Film Prepared by Sol-gel Method, Transactions of Nonferrous Metal Society of China,
Vol. 16, 2006, pp. s261–s265, https://doi.org/10.1016/S1003-6326(06)60187-8.
[16] V. R. Mudinepalli, L. Feng, W. C. Lin, B.S. Murty, Effect of Grain Size on Dielectric and Ferroelectric Properties of Nanostructured Ba0.8Sr0.2TiO3 Ceramics, Journal Advanced Ceramics, Vol. 4, No. 1, 2015, pp. 46-53, https://doi.org/10.1007/s40145-015-0130-8.
[17] S. Tinte, M. G. Stachiotti, S. R. Phillpot, M. Sepliarsky, D. Wolf, Ferroelectric and Dielectric Properties of Sol–gel Derived BaxSr1-xTiO3 Thin Films, Thin Solid Film, Vol. 424, 2003, pp. 70-74, https://doi.org/10.1016/S0040-6090(02)00918-5.
[18] M. Arshad, H. Du, M. S. Javed, A. Maqsood, I. Ashraf, S. Hussain, W. Ma, H. Ran, Fabrication, Structure, and Frequency-dependent Electrical and DielectricProperties of Sr-doped BaTiO3 Ceramics, Ceramics International, Vol. 46, 2020, pp. 2238-2246, https://doi.org/10.1016/j.ceramint.2019.09.208.
[19] B. Vigneshwaran, P. Kuppusami, S. Ajithkumar, H. Sreemoolanadhan, Study of Low Temperature‑dependent Structural, Dielectric, and Ferroelectric Properties of BaxSr1-xTiO3 (x=0.5, 0.6, 0.7) Ceramics, Journal of Materials Science: Materials in Electronics, Vol. 31, 2020, pp. 56, https://doi.org/10.1007/s10854-020-03593-3.
[20] N. Y. Chan, D. Y. Wang, Y. Wang, J. Y. Dai, H. L.W. Chan, The Structural and In-plane Dielectric/Ferroelectric Properties of The Epitaxial (Ba,Sr)(Zr,Ti)O3 Thin Films, Journal Applied Physics, Vol. 115, 2014, pp. 234102, https://doi.org/10.1063/1.4883963.