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Polarization switching in Hf0.5Zr0.5O2-dielectric stack: The role of dielectric layer thickness
Applied Physics Letters ( IF 3.5 ) Pub Date : 2021-09-24 , DOI: 10.1063/5.0056448
Atanu K. Saha 1 , Mengwei Si 1 , Peide D. Ye 1 , Sumeet K. Gupta 1
Affiliation  

Understanding the role of the dielectric (DE) layer in ferroelectric (FE) Hf0.5Zr0.5O2 (HZO) based devices (e.g., ferroelectric-field-effect-transistors, FE-FETs) is important to enable their application-driven optimizations. To that end, in this work, we systematically investigate the polarization switching mechanisms in FE–DE stacks and analyze their dependence on the dielectric layer thickness (TDE). First, we fabricate a HZO–Al2O3 (FE–DE) stack and experimentally demonstrate a decrease in remanent polarization and an increase in coercive voltage with an increase in TDE. As such dependencies are out of the scope of commonly used single domain polarization switching models, therefore, we argue that the consideration of the multi-domain model is essential for analyzing the polarization switching in HZO. Then, using phase-field simulations of the FE–DE stack, we show that an increase in TDE results in a larger number of reverse domains in the FE layer to suppress the depolarization field, which leads to a decrease in the remanent polarization and an increase in the coercive voltage. Furthermore, our analysis signifies that the polarization switching mechanism in HZO can be modulated from domain-nucleation based to domain-wall motion based by increasing the TDE and that can serve as a potential knob for application-specific optimization of FE-FETs. In addition, we show that the effective polarization–voltage characteristics of the FE layer in the FE–DE stack exhibit a negative slope region that leads to the charge enhancement effects in the FE–DE stack. While such effects are most commonly misinterpreted as either the transient effects or the stabilized single-domain negative capacitance effects, we demonstrate that the appearance of a negative slope in the hysteretic polarization–voltage characteristics is quasi-static in nature and that originates from the multi-domain polarization switching in the FE.

中文翻译:

Hf0.5Zr0.5O2-电介质堆栈中的极化转换:电介质层厚度的作用

了解电介质 (DE) 层在基于铁电 (FE) Hf 0.5 Zr 0.5 O 2 (HZO) 的器件(例如,铁电场效应晶体管、FE-FET)中的作用对于实现其应用驱动的优化非常重要. 为此,在这项工作中,我们系统地研究了 FE-DE 堆叠中的极化切换机制,并分析了它们对介电层厚度 ( T DE )的依赖性。首先,我们制造了 HZO-Al 2 O 3 (FE-DE) 叠层,并通过实验证明随着T DE的增加剩余极化减少和矫顽电压增加. 由于这种依赖性超出了常用的单域极化切换模型的范围,因此,我们认为多域模型的考虑对于分析 HZO 中的极化切换至关重要。然后,使用FE-DE堆叠的相场的模拟,我们表明,增加Ť DE导致反向域的更大数量的FE层来抑制去极化场,从而导致在剩余极化的降低和矫顽电压的增加。此外,我们的分析表示该偏振在HZO切换机构可从基于通过增加基于域的壁运动域成核调制Ť DE这可以作为 FE-FET 特定应用优化的潜在旋钮。此外,我们表明 FE-DE 堆栈中 FE 层的有效极化电压特性表现出负斜率区域,导致 FE-DE 堆栈中的电荷增强效应。虽然这种效应最常被误解为瞬态效应或稳定的单域负电容效应,但我们证明了滞后极化电压特性中负斜率的出现本质上是准静态的,并且源于多FE中的-域极化切换。
更新日期:2021-09-24
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