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

非技术描述：基于电可切换极化的非易失性铁电存储器已经大规模生产超过20年，市场规模估计为每年数亿美元。然而，一些挑战，例如缩放问题、高工作电压、相对较慢的速度和结构退化，限制了该技术的进一步发展，并呼吁材料科学和器件工程取得根本性进展。在这个项目中，主要研究人员研究了包括铁电钙钛矿和二维（2D）电子材料（即过渡金属二硫属化物）的混合异质结构。2D电子材料-其中最值得注意的是石墨烯-最近由于其独特的物理和化学性质而引起了前所未有的兴趣。2D和铁电材料的组合导致具有有前途的电子和存储特性的异质结构。铁电极化方向的抑制允许调制2D材料的电导率，这为开发具有上级特性（例如低功耗和更好的可扩展性）的存储器器件提供了基础。该项目将确定有前途的材料组合，用于操作电子存储器和逻辑器件。这加强了本科和研究生阶段的科学和工程教育。在这项研究中，沿着针对K-12学生及其家长、教师、少数民族和代表性不足的群体的外展活动，为本科生和研究生开发了一门新的纳米技术实验室课程。拟议研究的主要科学目标是实现包括2D材料和铁电（FE）薄膜的电子器件，该器件将表现出偏振控制的非线性特性。电子输运的易失性调制。该项目主要关注过渡金属二硫属化物的2D晶体，如MoS 2和WS 2。采用极化反转来调制（1）场效应晶体管器件的导电沟道中的面内输运，以及（2）跨越FE势垒的横向到面隧穿电导。这项研究的一个关键组成部分是调查工程分子层在2D-FE界面上的这些设备的功能特性的影响。对于气体和液体不可渗透的2D材料用于捕获和稳定铁电表面上的任何分子层，其用作在2D-FE界面处封装分子物质的有效覆盖层，并提供用于界面工程的简单和直接的方法。这项研究将推进对混合铁电基器件电子特性的基本理解，为可控电子势垒和通道的开发奠定持久的基础，影响从固态相变到表面电化学反应的广泛物理现象，并有助于纳米电子学的技术发展。

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.