Tuning Negative Capacitance in PbZr0.2Ti0.8O3/SrTiO3 Heterostructures via Layer Thickness Ratio
Tuning Negative Capacitance in PbZr0.2Ti0.8O3/SrTiO3 Heterostructures via Layer Thickness Ratio
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DOI：
10.1103/physrevapplied.16.034004
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发表时间：
2021-09-02
影响因子：
4.6
通讯作者：
Hong, Xia
中科院分区：
文献类型：
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作者：
Hao, Yifei;Li, Tianlin;Hong, Xia
在这项工作中，我们利用铁电介质层的厚度比r作为一个有效的调谐参数来控制的铁电极化和瞬态负电容（NC）状态的外延PbZr0.2Ti0.8O3/SrTiO 3双层异质结构。剩余极化随r的减小而单调减小，在临界比rc为8至7时，系统表现出从铁电到介电主导行为的突然转变，这与通过朗道理论建模的自由能分布的演变一致。对于较大的样品，在瞬态NC制度的极化切换动力学可以很好地描述的成核和生长模型，与窄分布的特征切换时间（t0）指向畴壁运动有限的行为。在rc的正下方，我们观察到t0的分布显著变宽，这可以归因于多畴态的出现。在r < 6的样品中，瞬态NC模式被淬灭，证实铁电有序被抑制。我们的研究为优化基于复合氧化物的NC晶体管的材料设计提供了关键信息，为其在低功率纳米电子学中的应用铺平了道路。
In this work, we exploit the ferroelectric-dielectric layer thickness ratio r as an effective tuning parameter to control the ferroelectric polarization and transient negative capacitance (NC) state in epitaxial PbZr0.2Ti0.8O3/SrTiO3 bilayer heterostructures. The remnant polarization decreases monotonically with decreasing r, with the system exhibiting an abrupt transition from ferroelectric to dielectric dominated behavior at a critical ratio rc of 8 to 7, which is consistent with the evolution of the free-energy profile modeled via Landau theory. For samples with larger, the polarization switching dynamics during the transient NC regime can be well described by the nucleation and growth model, with the narrow distribution of the characteristic switching time (t0) pointing to a domain-wall-motion-limited behavior. Right below rc, we observe a significantly broadened distribution of t0, which can be attributed to the emergence of a multidomain state. The transient NC mode is quenched in samples with r < 6, confirming that the ferroelectric order is suppressed. Our study provides critical information for optimizing the materials design for complex oxide-based NC transistors, paving the path for their application in low-power nanoelectronics.