Negative Capacitance in BaTiO3/BiFeO3 Bilayer Capacitors

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• 作者：Ya-Fei Hou ; Wei-Li Li ; Tian-Dong Zhang ; Yang Yu ; Ren-Lu Han ; Wei-Dong Fei
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：August 31, 2016
• 年：2016
• 卷：8
• 期：34
• 页码：22354-22360
• 全文大小：553K
• 年卷期：0
• ISSN：1944-8252

文摘

Negative capacitances provide an approach to reduce heat generations in field-effect transistors during the switch processes, which contributes to further miniaturization of the conventional integrated circuits. Although there are many studies about negative capacitances using ferroelectric materials, the direct observation of stable ferroelectric negative capacitances has rarely been reported. Here, we put forward a dc bias assistant model in bilayer capacitors, where one ferroelectric layer with large dielectric constant and the other ferroelectric layer with small dielectric constant are needed. Negative capacitances can be obtained when external dc bias electric fields are larger than a critical value. Based on the model, BaTiO₃/BiFeO₃ bilayer capacitors are chosen as study objects, and negative capacitances are observed directly. Additionally, the upward self-polarization effect in the ferroelectric layer reduces the critical electric field, which may provide a method for realizing zero and/or small dc bias assistant negative capacitances.