Imprint Control of BaTiO3 Thin Films via Chemically Induced Surface Polarization Pinning

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• 作者：Hyungwoo Lee ; Tae Heon Kim ; Jacob J. Patzner ; Haidong Lu ; Jung-Woo Lee ; Hua Zhou ; Wansoo Chang ; Mahesh K. Mahanthappa ; Evgeny Y. Tsymbal ; Alexei Gruverman ; Chang-Beom Eom
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：2400-2406
• 全文大小：472K
• 年卷期：0
• ISSN：1530-6992

文摘

Surface-adsorbed polar molecules can significantly alter the ferroelectric properties of oxide thin films. Thus, fundamental understanding and controlling the effect of surface adsorbates are crucial for the implementation of ferroelectric thin film devices, such as ferroelectric tunnel junctions. Herein, we report an imprint control of BaTiO₃ (BTO) thin films by chemically induced surface polarization pinning in the top few atomic layers of the water-exposed BTO films. Our studies based on synchrotron X-ray scattering and coherent Bragg rod analysis demonstrate that the chemically induced surface polarization is not switchable but reduces the polarization imprint and improves the bistability of ferroelectric phase in BTO tunnel junctions. We conclude that the chemical treatment of ferroelectric thin films with polar molecules may serve as a simple yet powerful strategy to enhance functional properties of ferroelectric tunnel junctions for their practical applications.