CAREER: Strain-driven phase transitions in 2D van der Waals based devices

提案标题职业：二维货车德瓦尔斯基器件中的应变驱动相变非技术摘要传统上，计算技术进步的焦点强烈依赖于构成几乎所有集成电路的场效应晶体管（FET）的持续缩小。由于晶体管缩放的基本物理和经济极限现在正在达到，因此正在探索新类型的器件，以增加传统晶体管开关之外的功能。这个项目探讨了应变在二维（2D）结合材料中的应用，这样施加的拉伸或压缩可能会在这些系统中引起各种相变。由于这些相变不限于如在常规晶体管的开/关状态中的导电与不导电，因此可以通过应变下材料性质的其他变化来设计附加功能。这种类型的应变诱导相变器件不会在与传统晶体管相同的物理机制下工作，因此不受相同的限制。通过影响现代纳米电子学的构建块，可能会对当前由于传统晶体管的各种功率、速度或效率限制而受到限制的计算技术的各个方面产生很大影响。该项目还试图利用研究框架，通过与罗切斯特大学伊士曼音乐学院的联系，向传统上代表性不足的社区推广科学、技术、工程和数学（STEM）。活动的例子包括运行在音乐和电子暑期教育课程，以当地7-12年级的学生，创造非传统的仪器，可能会被用于现场音乐会performance.Technical AbstractThis项目旨在了解的基本原则，使用设备规模的栅极可控应变在二维（2D）键合材料，以创造新型的相变晶体管。通过探索使用应变的晶体管切换的新机制，可以克服与常规场效应晶体管操作相关联的限制。随着二维材料类中各种各样的相接近应变可调相变，有机会为各种各样的门可控奇异物质态奠定基础。在这个项目中使用的设备平台使用动态应变施加从铁电氧化物与静态薄膜应力帽层相结合，以证明在Mo 1-xWxTe 2类的二维材料的相变。使用MoTe 2半金属到半导体相变作为起点，确定了可能仍然限制在2D系统中实现可靠的动态器件规模应变的关键问题，其目标是将这种“应变子”概念扩展到更高耐久性更高产量的操作，以及添加新的相来控制Mo 1-xWxTe 2类材料。此外，从单个2D系统中的室温操作中学习的基本概念允许将该动态应变工程概念转化为低温和货车范德华异质结构，广泛扩展了动态应变工程在二维系统中的应用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响进行评估，被认为值得支持审查标准。

Proposal TitleCAREER: Strain-driven phase transitions in two-dimensional van der Waals based devicesNon-technical AbstractThe conventional focus for advancements in computing have strongly relied on the continued shrinking of the field-effect transistors (FET) that makes up almost all integrated circuits. Since the fundamental physical and economic limits of transistor scaling are now being reached, new types of devices are being explored for added functionality beyond conventional transistor switching. This project explores the use of strain in two dimensionally (2D) bonded materials, such that applied stretching or compression may induce various phase-changes in these systems. Since these phase-changes are not limited to electrically conducting versus non-conducting as in on/off states of conventional transistors, additional functionality may be engineered through other changes in materials properties under strain. This type of strain-induced phase-change device would not operate under the same physical mechanism as conventional transistors, and therefore are not subject to the same limitations. By impacting the building blocks of modern nanoelectronics, there may be large impacts in various aspects of computing technology that are currently limited due to various power, speed, or efficiency limitations of conventional transistors. This project also seeks to use the research framework to promote science, technology, engineering and mathematics (STEM) to traditionally underrepresented communities by connecting with the Eastman School of Music at the University of Rochester. Examples of activities include running summer educational courses in music and electronics to local grade 7-12 students to create unconventional instruments that may be used in live concert performances.Technical AbstractThis project seeks to understand the foundational principles of using device-scale gate-controllable strain in two-dimensional (2D)-bonded materials to create new types of phase change transistors. By exploring a new mechanism of transistor switching using strain, limitations associated with conventional field-effect transistor operations may be overcome. With the wide variety of phases in the two-dimensional materials class close to strain-tunable phase transitions, the opportunity exists to set the basis for a wide variety of gate-controllable exotic states of matter. The device platform used in this project uses dynamic strain applied from ferroelectric oxides in combination with static thin film stress capping layers to demonstrate phase-switching in the Mo1-xWxTe2 class of two-dimensional materials. Using the MoTe2 semimetallic to semiconducting phase transition as a starting point, critical issues are identified that may still limit the implementation of reliable dynamic device scale strain in 2D systems, with the goal of expanding this "straintronic" concept to higher-endurance higher-yield operation as well as adding new phases to control within the Mo1-xWxTe2 class of materials. Additionally, learned foundational concepts from room-temperature operation in single 2D systems allow for the translation of this dynamic strain engineering concept to low temperatures and to van der Waals heterostructures, widely expanding the applicability of dynamic strain engineering in 2D systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.