Ferroelectric HfO2 on Germanium Tunnel Junctions Towards Sub-Femto Joule Switching

锗隧道结上的铁电 HfO2 实现亚飞秒焦耳切换

• 批准号: 1610387
• 负责人: Toshikazu Nishida
• 金额: $ 40万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610387&HistoricalAwards=false
• 关键词: Ferroelectric; HfO2; Germanium; Tunnel; Junctions

The rapid increase in data generated by mobile devices and computers necessitates research and development of advanced solid-state data storage technologies. The ferroelectric effect, a switchable polarization charge, which occurs in certain materials combined together with an advanced memory device concept provides a promising approach to achieve a transformative improvement in non-volatile memory technologies. The discovery of ferroelectricity in lead-free hafnium dioxide thin films in 2011 offers a sustainable route for further scaling of the next generation of manufacturable, low-power, and high performance nonvolatile memory ferroelectric devices. In this project, an advanced device concept known as a ferroelectric tunnel junction (FTJ) will be investigated using the ferroelectric hafnium dioxide thin films. In a FTJ, the tunneling electroresistance is switched between a low and a high value by switching the polarization direction (internal electric field). Numerical studies indicate that the hafnium dioxide-based FTJ can yield substantial reductions in the amount of power required to store data. In a two-pronged approach, experiments and numerical modeling will be conducted to test the numerical models and to advance the fundamental understanding and state-of-the-art in nonvolatile FTJ memory technology using hafnium dioxide thin films.The overriding goal of the project is to understand and tailor the atomic structure of the ferroelectric phase of hafnium dioxide in thin film capacitors, thereby enabling complementary metal-oxide-semiconductor (CMOS)-compatible FTJs. A comprehensive and methodological study evaluating the deposition and processing conditions of hafnium dioxide-based thin film ferroelectrics will provide critical insights about the effect of impurities, dopants, film growth and annealing temperatures, and interfacial stability that influence the ferroelectric properties. These studies will pave the way toward investigating the physical limits of ferroelectric hafnium dioxide-based films and the realization of CMOS-compatible and scalable FTJs. Recent studies on macroscopic variation of the dopants concentration as well as the atomic layering of mixed mono-layers of dopants in hafnium dioxide suggest extreme possibilities in fine-tuning ferroelectric properties of doped hafnium dioxide thin films. The discovery of CMOS compatible and scalable ferroelectric hafnium dioxide offers a unique opportunity to investigate the performance potential of CMOS compatible hafnium dioxide FTJ through carefully coupled theoretical and experimental investigation. Numerical studies indicate that ferroelectric hafnium dioxide FTJ on germanium substrate can approach sub-femto Joule/bit for a feature size of F=20nm. This ability to experimentally tune the characteristics of the ferroelectric hafnium dioxide thin films of varying thickness coupled with advanced ab initio material and device simulation enable this investigation of the performance limits of FTJ devices employing ferroelectric hafnium dioxide on germanium.

由移动的设备和计算机产生的数据的快速增长使得研究和开发先进的固态数据存储技术成为必要。 在某些材料中发生的铁电效应（可切换的极化电荷）与先进的存储器器件概念结合在一起，提供了一种有前途的方法来实现非易失性存储器技术的变革性改进。 2011年在无铅二氧化铪薄膜中发现的铁电性为下一代可制造、低功耗和高性能非易失性存储器铁电器件的进一步扩展提供了可持续的途径。 在这个项目中，一个先进的器件概念称为铁电隧道结（FTJ）将使用铁电二氧化铪薄膜进行研究。 在FTJ中，通过切换极化方向（内部电场），隧道电阻在低值和高值之间切换。 数值研究表明，基于二氧化铪的FTJ可以大大降低存储数据所需的功率。 本项目将采用实验和数值模拟双管齐下的方法，以测试数值模型，并推进对使用二氧化铪薄膜的非易失性FTJ存储器技术的基本理解和最新技术水平。该项目的首要目标是理解和调整薄膜电容器中二氧化铪铁电相的原子结构，从而实现互补金属氧化物半导体（CMOS）兼容的FTJ。 一个全面的和方法学的研究评估二氧化铪基薄膜铁电体的沉积和加工条件将提供关键的见解杂质，掺杂剂，薄膜生长和退火温度的影响，以及界面稳定性，影响铁电性能。这些研究将为研究铁电二氧化铪基薄膜的物理极限和实现CMOS兼容和可扩展的FTJ铺平道路。 最近的研究宏观变化的掺杂剂浓度，以及原子分层的混合单层的掺杂剂在二氧化铪薄膜的微调铁电性能的掺杂二氧化铪薄膜的建议极端的可能性。CMOS兼容和可扩展的铁电二氧化铪的发现提供了一个独特的机会，通过仔细耦合的理论和实验研究，研究CMOS兼容的二氧化铪FTJ的性能潜力。数值研究表明，对于F= 20 nm的特征尺寸，锗衬底上的铁电二氧化铪FTJ可以达到亚毫微微焦耳/位。这种能力，以实验方式调整与先进的从头算材料和设备模拟耦合的不同厚度的铁电二氧化铪薄膜的特性，使FTJ设备的性能限制的调查，采用锗上的铁电二氧化铪。

项目成果

High tunnelling electroresistance in a ferroelectric van der Waals heterojunction via giant barrier height modulation

• DOI: 10.1038/s41928-020-0441-9
• 发表时间: 2020-07-06
• 期刊: NATURE ELECTRONICS
• 影响因子: 34.3
• 作者: Wu, Jiangbin;Chen, Hung-Yu;Wang, Han
• 通讯作者: Wang, Han