GOALI: Negative Capacitance in Epitaxial Oxide Heterostructures

目标：外延氧化物异质结构中的负电容

• 批准号: 1207342
• 负责人: John Ekerdt
• 金额: $ 48万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207342&HistoricalAwards=false
• 关键词: GOALI; Negative; Capacitance; Epitaxial; Oxide

This project is jointly funded by the Electronic and Photonic Materials Program (EPM) and Ceramics Program (CER) in the Division of Materials Research (DMR).Technical Description: This GOALI project explores the fundamental materials science problems of integrating a single-crystalline, single-domain ferroelectric material (with polarization out of plane) onto silicon. A ferroelectric layer in series with a dielectric is predicted to produce negative capacitance, which will lower the sub-threshold slope of a field effect transistor and significantly lower the power dissipated in a transistor. This research project develops the materials and the fundamental understanding necessary to make the predictions a reality. Molecular beam epitaxy is used to grow strontium titanate epitaxially on single-crystal silicon as a buffer layer for the nucleation and growth of single-crystal ferroelectric films, such as barium titanate. The research explores routes to integrate these single- crystal layers on silicon, approaches to achieving out-of-plane polarization in the ferroelectric layer for thicknesses up to 50 nanometers, approaches to achieving a single-domain ferroelectric state, and integration of these layers into transistor devices to harness the negative capacitance state of the heterolayers and realize sub-threshold slopes less than 60 millivolts per decade. The experimental growth studies are guided by ab-initio theory, and materials properties are characterized using in-situ and ex-situ methods.Non-technical Description: Scaling of the complementary metal oxide semiconductor (CMOS) technology is at the heart of Moore's law; it is driven by the desire to produce ever faster field effect transistors. However, the faster the transistor is the more heat it generates in the switching process. New device concepts are required to enable significantly lower power dissipation and to realize the full speed potential for the smaller devices. This research project explores one of the new device concepts of using a ferroelectric/dielectric composite film in place of the dielectric that is currently used in field effect transistors - a concept that is yet to be realized because of the challenges in growing the layers with the proper crystal structure and orientation on the silicon surface that forms the transistor. The research combines an interdisciplinary team and explores growth and properties of barium titanate layers (the ferroelectric) on strontium titanate (the dielectric) on a silicon wafer. The research partners university researchers with a technology leader in advanced device design to broaden the student experience as they are exposed to problem definition that keeps the end goal of developing a viable technology front and center. The outreach activities are aimed at attracting high-school female students to physical sciences and engineering; in collaboration with the physics instructors in local high schools, the students spend summers in research groups at the University of Texas at Austin and participate in real science in a supportive environment.

该项目由材料研究部 (DMR) 电子和光子材料计划 (EPM) 和陶瓷计划 (CER) 联合资助。技术说明：该 GOALI 项目探索集成单晶、单畴铁电材料（平面外极化）到硅上。预计与电介质串联的铁电层会产生负电容，这将降低场效应晶体管的亚阈值斜率并显着降低晶体管中的功耗。该研究项目开发了使预测成为现实所需的材料和基本理解。分子束外延用于在单晶硅上外延生长钛酸锶，作为单晶铁电薄膜（例如钛酸钡）成核和生长的缓冲层。该研究探索了将这些单晶层集成在硅上的路线、在厚度高达 50 纳米的铁电层中实现面外极化的方法、实现单域铁电态的方法以及将这些层集成到晶体管器件利用异质层的负电容状态并实现每十倍频程小于 60 毫伏的亚阈值斜率。实验生长研究以从头算理论为指导，并使用原位和异位方法表征材料特性。非技术描述：互补金属氧化物半导体 (CMOS) 技术的扩展是摩尔定律的核心;它是由生产更快的场效应晶体管的愿望驱动的。然而，晶体管速度越快，在开关过程中产生的热量就越多。需要新的器件概念来显着降低功耗并实现较小器件的全速潜力。该研究项目探索了一种新的器件概念，即使用铁电/介电复合膜代替目前场效应晶体管中使用的电介质，这一概念尚未实现，因为用铁电/介电复合膜生长层存在挑战。形成晶体管的硅表面上正确的晶体结构和取向。该研究结合了跨学科团队，探索硅晶片上钛酸锶（电介质）上钛酸钡层（铁电体）的生长和特性。该研究与大学研究人员和先进设备设计领域的技术领导者合作，以拓宽学生的体验，因为他们接触到问题定义，从而保持开发可行的技术前沿和中心的最终目标。推广活动旨在吸引高中女生学习物理科学和工程；学生们与当地高中的物理教师合作，在德克萨斯大学奥斯汀分校的研究小组中度过暑假，并在支持性的环境中参与真正的科学活动。