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，经济实惠且高效的光学和电存储器是知识和思想保存和传播的基础，经历相变的材料（例如 DVD 中常用的硫属化物）尤其有前途。新兴应用将存储器与高速计算相结合，但需要相对较大的编程能量，该能量与所切换的材料体积成正比，在二维 (2D) 材料（例如碲化钼 (MoTe2)）中编码数据提供了直接的方法。在可经历相变的现有二维材料中，MoTe2 预计是最节能的，但明显缺乏实验证据来支持控制机制、动力学和局限性的相互矛盾的理论模型。该团队提出利用动态光学测量技术与超高分辨率透射电子显微镜相结合来解决这一知识空白，克服了先前工作的实验限制，为相关的二维材料提供了新的线索。该团队致力于通过互动研讨会的方式，对来自 STEM 领域历来代表性不足的地区的中学生和高中生进行有关日常生活中纳米材料的主题教育。该项目还为两名研究生提供纳米制造和表征技术方面的培训，并在夏季接待来自代表性不足群体的本科生，以扩大对 STEM 相关领域的参与。技术摘要：相变材料使光电存储器有潜力通过以光速处理存储器中的信息来改变低能量、非冯·诺依曼计算架构，原子平坦的相变材料（例如MoTe2及其合金Mo1-xWxTe2）将进一步减少能量消耗。通过大幅减少经历相变的活性体积来配置其状态所需的能量虽然在MoTe-2和相关材料中观察到光诱导相变，但与采用类似观察的情况不同，这些转变是不可逆的。电化学掺杂和机械应变有限的经验证据和理论模型表明 Te 空位在相变过程中发挥着核心作用，但对 MoTe2 中 2H 和 1T' 相之间光学转换的动力学和物理机制的清晰理解仍然难以实现。该团队提出，可以通过材料合成、封装和 W 合金来控制 MoTe2 中的光致结构转变，从而提高运行速度、提高可靠性并降低开关能量。该项目包含以下三个目标：（1）通过设计MoTe2生长过程中Te空位的浓度来确定Te空位对光开关功率的影响；（2）封装MoTe2以减少光激发期间的Te损失——预期的机制(3)将MoTe2与W合金化，设计出一种用于高效、可重写光电相变存储器的最佳二维材料。该方法通过探索现有实验技术的时间限制。所提出的研究有望通过利用 MoTe2 的结构变换来编码信息，从而实现高速、非易失性和高效的数据存储。光学和电光技术来解决有关 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矛盾的理论模型，预计对 MoTe2 的相变过程有新的见解。使其能够广泛应用于数据存储以外的领域，例如神经拟态计算、电光转换、柔性电子以及可重构拓扑和量子器件。该奖项反映了 NSF 的法定使命，并通过利用基金会的智力优势进行评估，认为值得支持以及更广泛的影响审查标准。

项目成果

期刊论文数量（7）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Integrated optical memristors

集成光学忆阻器

DOI：
10.1038/s41566-023-01217-w
发表时间：
2023-05-29
期刊：
Nature Photonics
影响因子：
35
作者：
N. Youngblood;Carlos A. Ríos Ocampo;W. Pernice;H. Bhaskaran
通讯作者：
H. Bhaskaran

Coherent Photonic Crossbar Arrays for Large-Scale Matrix-Matrix Multiplication

用于大规模矩阵-矩阵乘法的相干光子交叉阵列

DOI：
10.1109/jstqe.2022.3171167
发表时间：
2023-03-01
期刊：
IEEE Journal of Selected Topics in Quantum Electronics
影响因子：
4.9
作者：
N. Youngblood
通讯作者：
N. Youngblood

Engineering photonic environments for two-dimensional materials

二维材料的工程光子环境

DOI：
10.1515/nanoph-2020-0524
发表时间：
2020-09-19
期刊：
Nanophotonics
影响因子：
7.5
作者：
Xuezhi Ma;N. Youngblood;Xiaoze Liu;Yan Cheng;Preston Cunha;Kaushik Kudtarkar;Xiaomu Wang;Shoufeng Lan
通讯作者：
Shoufeng Lan

Reconfigurable Low-Emissivity Optical Coating Using Ultrathin Phase Change Materials

使用超薄相变材料的可重构低发射率光学涂层

DOI：
10.1021/acsphotonics.1c01128.s002
发表时间：
2021-12-17
期刊：
ACS Photonics
影响因子：
7
作者：
N. Youngblood;Clément Talagr;B. Porter;C. G. Galante;S. Kneepkens;G. Triggs;Syed Ghazi Sarwat;D. Yarmolich;R. S. Bonilla;P. Hosseini;Robert A. Taylor;H. Bhaskaran
通讯作者：
H. Bhaskaran

Photonic (computational) memories: tunable nanophotonics for data storage and computing

光子（计算）存储器：用于数据存储和计算的可调谐纳米光子学