Polarization-mediated modulation of electronic properties of hybrid ferroelectric-based heterostructures

基于电可开关极化的非易失性铁电存储器已经大规模生产了20多年，市场规模估计在每年数亿美元。然而，许多挑战，如缩放问题、高工作电压、相对较慢的速度和结构退化，限制了这项技术的进一步发展，并要求在材料科学和器件工程方面取得根本性进展。在这个项目中，主要研究人员研究了由铁电钙钛矿和二维（2D）电子材料，即过渡金属二硫族化合物组成的杂化异质结构。二维电子材料——其中最引人注目的是石墨烯——由于其独特的物理和化学性质，最近引起了前所未有的兴趣。二维和铁电材料的结合产生了具有良好电子和存储性能的异质结构。铁电极化方向的反转允许对二维材料的电导率进行调制，这为开发具有低功耗和更好的可扩展性等优越特性的存储器件提供了基础。该项目将确定在操作电子存储器和逻辑器件中实现的有前途的材料组合。加强本科和研究生阶段的科学和工程教育。在这项研究中，为本科生和研究生开发了一门新的纳米技术实验课程，并针对K-12学生及其家长、教师、少数民族和未被充分代表的群体开展了外展活动。技术描述：拟议研究的主要科学目标是实现由二维材料和铁电（FE）薄膜组成的电子器件，这些电子器件将表现出极化控制的非易失性电子输运调制。本项目主要研究过渡金属二硫化物的二维晶体，如MoS2和WS2。极化反转用于调制(1)场效应晶体管器件导电通道中的平面内输运，以及(2)穿过FE势垒的垂直于平面隧穿电导。本研究的一个关键组成部分是研究2D-FE界面上的工程分子层对这些器件功能特性的影响。二维材料不渗透气体和液体，用于捕获和稳定铁电表面上的任何分子层，作为有效的覆盖层，在2D- fe界面上包封分子物种，为界面工程提供了一种简单直接的方法。这项研究将促进对混合铁电器件电子特性的基本理解，为开发可控电子屏障和通道奠定持久的基础，影响从固态相变到表面电化学反应的广泛物理现象，并为纳米电子学的技术发展做出贡献。

Polarization-controlled modulation of electronic properties of hybrid ferroelectric-based heterostructuresNon-technical Description: Nonvolatile ferroelectric memories, based on electrically switchable polarization, have been in mass production for over 20 years with a market size estimated to be in the hundreds of millions of dollars per year. However, a number of challenges, such as scaling issues, high operating voltages, relatively slow speed and structural degradation, limit further development of this technology and call for fundamental advances in materials science and device engineering. In this project, the principal investigators study hybrid heterostructures comprising ferroelectric perovskites and two-dimensional (2D) electronic materials, namely transition metal dichalcogenides. 2D electronic materials - the most notable among them being graphene - have recently attracted an unprecedented interest due to their unique physical and chemical properties. A combination of 2D and ferroelectric materials results in heterostructures with promising electronic and memory properties. Reversal of ferroelectric polarization direction allows modulation of the electrical conductivity of a 2D material, which provides a basis for the development of memory devices with superior characteristics, such as low power consumption and better scalability. This project will identify promising materials combinations for implementation in operational electronic memories and logic devices. The enhances science and engineering education at both undergraduate and graduate level. Within this research, a new nanotechnology laboratory course for undergraduate and graduate students is developed along with the outreach activities targeting K-12 students and their parents, teachers, minorities and underrepresented groups.Technical Description: The main scientific objective of the proposed research is implementation of the electronic devices comprising 2D materials and ferroelectric (FE) thin films that will exhibit polarization-controlled non-volatile modulation of the electronic transport. This project primarily focuses on 2D crystals of transition metal dichalcogenides, such as MoS2 and WS2. Polarization reversal is employed to modulate (1) the in-plane transport in a conducting channel of a field-effect transistor device, and (2) the perpendicular-to-plane tunneling conductance across the FE barrier. A critical component of this research is investigation of the effect of engineered molecular layers at the 2D-FE interfaces on the functional properties of these devices. The 2D materials, which are impermeable for gases and liquids, are used to trap and stabilize any molecular layer on a ferroelectric surface serving as effective cover layers for encapsulation of molecular species at the 2D-FE interface and providing a simple and straightforward method for interface engineering. This research will advance the fundamental understanding of the electronic properties of hybrid ferroelectric-based devices, build a lasting basis for the exploitation of controllable electronic barriers and channels, impact a broad range of physical phenomena from solid-state phase transitions to surface electrochemical reactions and contribute to technological development of nanoscale electronics.