Inversion Charge Boost and Transient Steep-Slope Induced by Free-Charge-Polarization Mismatch in a Ferroelectric-Metal–Oxide–Semiconductor Capacitor
Inversion Charge Boost and Transient Steep-Slope Induced by Free-Charge-Polarization Mismatch in a Ferroelectric-Metal–Oxide–Semiconductor Capacitor
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DOI：
10.1109/jxcdc.2018.2846202
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发表时间：
2018-04
影响因子：
2.4
通讯作者：
Sou-Chi Chang;U. Avci;D. Nikonov;I. Young
中科院分区：
文献类型：
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作者：
Sou-Chi Chang;U. Avci;D. Nikonov;I. Young
本文用串联电阻从理论上研究了铁电(FE)-金属氧化物-半导体（MOS）电容器的瞬态行为。结果表明，与传统的高k介电MOS电容器相比，FE MOS电容器由于自由电荷极化失配驱动的瞬态陡亚阈值摆幅（SS）可以实现显著的反转电荷升压。实验还表明，瞬态陡坡SS的观测不仅与测量时间有关，还与朗道平均场理论下的黏度系数有关，黏度系数通常表示与畴形核和传播相关的平均FE时间响应。因此，本文不仅建立了一个理论框架，描述了FE MOS电容器中反向电荷升压的物理成因，而且表明稳态下FE MOS电容器退极化效应的关键特征应该是反向电荷升压，而不是陡峭的SS（例如室温下低于60 mV/ 10年），由于测量时间远远大于本征FE响应，因此无法通过实验观察到。最后，从粘度系数对倒置电荷升压的影响出发，概述了适用于下一代高速低功耗数字开关的场效应晶体管的FE响应所需的材料目标。
In this paper, the transient behavior of a ferroelectric (FE)-metal–oxide–semiconductor (MOS) capacitor is theoretically investigated with a series resistor. It is shown that compared with a conventional high-k dielectric MOS capacitor, a significant inversion charge boost can be achieved by an FE MOS capacitor due to a transient steep subthreshold swing (SS) driven by the free-charge-polarization mismatch. It is also shown that the observation of transient steep SS in the experiment significantly depends not only on the measurement time but also on the viscosity coefficient under Landau’s mean field theory, which in general represents the average FE time response associated with the domain nucleation and propagation. Therefore, this paper not only establishes a theoretical framework that describes the physical origin behind the inversion charge-boost in an FE MOS capacitor but also shows that the key feature of depolarization effect on an FE MOS capacitor in the steady state should be the inversion charge boost, rather than the steep SS (e.g., sub-60 mV/decade at room temperature), which cannot be experimentally observed as the measurement time is much longer than the intrinsic FE response. Finally, from the effect of viscosity coefficient on inversion charge boost, we outline the required material targets for the FE response in field-effect transistors to be applicable for next-generation high-speed and low-power digital switches.