title: Negative Capacitance in BaTiO3/BiFeO3 Bilayer Capacitors.
abstract: 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.
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Ya-Fei
authors: YF
authors: Hou
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Wei-Li
authors: WL
authors: Li
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Tian-Dong
authors: TD
authors: Zhang
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Yang
authors: Y
authors: Yu
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Ren-Lu
authors: RL
authors: Han
authors: National Key LAB for Advanced Welding and Joining, and ‡National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology , Harbin 150001, P. R. China.
authors: Wei-Dong
authors: WD
authors: Fei
keywords: BaTiO3/BiFeO3 bilayer capacitor; critical electric field; dc bias assistant model; ferroelectric; negative capacitance; self-polarization effect