Elucidating Structural Transformations in MoTe2 for Efficient Optoelectronic Memory

阐明 MoTe2 的结构转变以实现高效光电存储器

基本信息

批准号：
2003325
负责人：
Nathan Youngblood
金额：
$ 50.2万
依托单位：
University of Pittsburgh
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003325&HistoricalAwards=false
关键词：
Elucidating Structural Transformations MoTe2 Efficient

项目摘要

Non-technical abstract:In the information age, affordable and efficient optical and electrical memory is foundational to the preservation and dissemination of knowledge and ideas. Materials which undergo a phase transition, such as chalcogenides that are commonly used in DVDs, are especially promising for emerging applications which combine memory with high-speed computing but require relatively large programming energies which is proportional to the volume of material switched. Encoding data in two-dimensional (2D) materials such as molybdenum tellurides (MoTe2) provides a direct route to overcome this fundamental limitation. Among available 2D materials which can undergo a phase transition, MoTe2 is predicted to be the most energy efficient, but there is a distinct lack of experimental evidence to support conflicting theoretical models governing the mechanisms, dynamics, and limitations of optically-induced phase transformations in MoTe2. The team proposes to address this knowledge gap using dynamic optical measurement techniques in combination with ultrahigh-resolution transmission electron microscopy. The project overcomes the experimental limitations of prior works to shed new light on related 2D materials for applications requiring high-speed, reliable, and efficient optoelectronic memory. The team seeks to educate middle- and high-school students on topics related to nanomaterials in daily life from districts with historically under-represented minorities in STEM fields using a combination of interactive workshops and virtual reality tools. This project also provides training for two graduate students in nanofabrication and characterization techniques and hosts undergraduates from underrepresented groups during the summer months to broaden participation in STEM-related fields.Technical abstract:Phase-change materials that enable optoelectronic memory have the potential to transform low-energy, non-von Neumann computing architectures by processing information in memory at the speed of light. A phase-change material that is atomically flat (e.g. MoTe2 and its alloy Mo1-xWxTe2) would further reduce the energy required to configure its state by drastically reducing the active volume undergoing a phase transition. While optically induced phase transformations have been observed in MoTe¬2 and related materials, these transformations have been irreversible unlike similar observations employing electrochemical doping and mechanical strain. Limited empirical evidence and theoretical modeling indicates Te vacancies play a central role in the phase transition process, but a clear understanding of the dynamics and physical mechanism of optical switching between the 2H and 1T’ phases in MoTe2 remains elusive to date. The team proposes that optically induced structural transformations can be controlled in MoTe2 through material synthesis, encapsulation, and W-alloying, resulting in higher operating speeds, improved reliability, and lower switching energies. To test this hypothesis, the project contains the following three aims: (1) determine the influence of Te vacancies on the optical switching power by engineering the concentration of Te vacancies during the MoTe2 growth process; (2) encapsulate MoTe2 to reduce Te loss during optical excitation—the expected mechanism preventing reversible optical switching; and (3) alloy MoTe2 with W to engineer an optimal 2D material for efficient and rewriteable optoelectronic phase-change memory. The proposed approach overcomes the temporal limitations of prior experimental techniques by probing the phase-transition process in the optical domain. The proposed research is expected to enable the development of high-speed, non-volatile, and efficient data storage by exploiting structural transformations in MoTe2 to encode information. This study is the first to use a combination of optical and electro-optical techniques to resolve conflicting theoretical models regarding the phase transformation mechanisms, dynamics, and optimal stoichiometry of MoTe2 and its alloy Mo1-xWxTe2. New insights into phase-transformation process of MoTe2 are expected to have broad application to fields beyond data storage, such as neuromorphic computing, electro-optic conversion, flexible electronics, and reconfigurable topological and quantum devices.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.

非技术摘要：在信息时代，负担得起，有效的光学和电气记忆是知识和思想的准备和传播的基础。发生相变的材料，例如在DVD中常用的硫代基化剂，对于将记忆与高速计算相结合但需要相对较大的编程能量的新兴应用特别有前途，该应用与切换的材料量成比例。编码二维（2D）材料（例如钼酸钼（MOTE2））的数据提供了克服这一基本限制的直接途径。在可以进行相变的可用2D材料中，MOTE2被预计是最节能的，但是缺乏实验证据来支持MOTE2中光学诱导的相变的机制，动力学和局限性冲突。团队建议使用动态光学测量技术与超高分辨率传输电子显微镜结合使用动态光学测量技术来解决这一知识差距。该项目克服了先前作品的实验局限性，为需要高速，可靠和有效的光电记忆的应用提供了有关相关2D材料的新启示。该团队试图通过使用互动式研讨会和虚拟现实工具的组合结合了历史上代表性不足的STEM领域中少数群体的纳米材料的主题教育与纳米材料有关的主题。该项目还为两名研究生提供了纳米化和表征技术的培训，并在夏季几个月中从代表性不足的组中的本科生提供了培训，以扩大与STEM相关的领域的参与。技术摘要：启用OptoElectRonic存储器的相变材料有可能通过较低的内部雾化，非von neumann neumann neumann计算的架构来转换型号的型号，以进行架构的启动，以构建型号的构造量来实现型号的信息，以构建信息，以构建型号的信息，以促进型号的信息，以实现型号的信息，以实现型号的信息，以构建型号的信息，以促进型号的信息，以构建型号的信息，以构建型号的启动。在原子上平坦的相位变化材料（例如Mote2及其合金MO1-XWXTE2）将进一步降低配置其状态所需的能量，从而大大降低经过相变的活性体积。尽管在MOTE -2和相关材料中观察到了光学诱导的相变，但与使用电化学掺杂和机械应变的类似观察结果不同，这些转换是不可逆的。有限的经验证据和理论建模表明，空位在相变过程中起着核心作用，但是对Mote2中2H和1T阶段之间光学切换的动态和物理机理有清晰的理解，至今仍是弹性的。可以通过材料合成，封装和W-Alyoying在Mote2中控制光学诱导结构转换的团队建议，从而导致更高的工作速度，提高可靠性和较低的开关能量。为了检验该假设，该项目包含以下三个目的：（1）通过在MOTE2增长过程中设计TE空缺的浓度来确定TE空位对光学开关功率的影响；（2）封装Mote2，以减少光兴奋期间的TE损失 - 预期的机制可防止可逆光学切换；（3）与W合金MOTE2一起设计最佳的2D材料，以高效且可重写的光电相位变化内存。提出的方法通过探测光学域中的相变过程来克服先前实验技术的暂时局限性。拟议的研究有望通过利用MOTE2中的结构转换来编码信息来开发高速，非易失性和有效的数据存储。这项研究是第一个使用光学和电流技术组合来解决有关MOTE2及其合金MO1-XWXTE2的相变机制，动力学和最佳化学计量的相互冲突的理论模型。预计MOTE2对相位转换过程的新见解有望在数据存储以外的领域中广泛应用，例如神经形态计算，电磁转换，灵活的电子设备以及可重新配置的拓扑和量子设备。该奖项反映了NSF的法定任务，并通过评估了Intellitia and Intellia and Intellitia and Infcessia and Infcordial and Intellitial and Infcordial and Intfactia and Intellitial and Intellit and Intellitial and Intellit and Intellit and Intellit and Intellit and Intellit and Intellit and Funditial and Interviatial and Funditial的支持。