Real Time Quantification of Diffusion and Alloying in Atomically Thin Capillaries

原子薄毛细管中扩散和合金化的实时定量

• 批准号: 1905853
• 负责人: Deep Jariwala
• 金额: $ 45万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905853&HistoricalAwards=false
• 关键词: Real; Time; Quantification; Diffusion; Alloying

Non-technical description: Two-dimensional (2D) materials have been the subject of intense scientific investigation as their atomically thin nature leads to a wide variety of novel optical and electronic properties. While numerous fundamental physical property investigations and device demonstrations have been performed, there is still a significant knowledge gap in understanding how relevant processing and operation conditions such as structural confinement (encapsulation), high temperature and large current flows affect their structure and performance. Such conditions are commonly encountered during high performance device operation in modern microelectronics. Understanding these properties is therefore critical for understanding the alloying and doping, heterojunction and contact formation, as well as electrical and thermal failure. This project helps understand the fundamental thermodynamic processes and transformations that these materials undergo under extreme physical confinement and temperatures by direct visualization and spectroscopic analysis with an electron beam inside an electron microscope. These experiments are then coupled with nanoscale optical imaging techniques to correlate the structural transformations with optical and electronic property changes. These investigations advance our fundamental knowledge, and help frame design rules for synthesis, processing and device operation considerations. This project also includes next generation workforce preparation by training graduate students in forefront materials synthesis, state of the art microscopy and optical spectroscopy. It also entails workforce development for undergraduate students via the Materials Research Science and Engineering Center's research experience for undergraduate student program. Finally, the research outcomes, and specifically interactive models, are disseminated to the broader public via public lectures, science outreach activities and undergraduate as well as graduate class room education. Technical description: The research goals of this project is to investigate structural phase transformations and diffusion phenomena in van der Waals layered two-dimensional chalcogenide systems. A combination of near-field optical spectroscopy and in-situ transmission electron microscopy methods, combined with unique sample preparation on pre-patterned substrates are used to investigate the impact of structural confinement, current and temperature. The samples are prepared via mechanical exfoliaton and stacking, as well as via chemical vapor deposition growth. The work exploits the ability to layer atomically-thin layers of these chalcogenides and their vertical heterostructures and then encapsulate them in inert and refractory layers such as graphite or boron nitride. In addition, the ability to laterally stitch and grow in-plane heterostructures via chemical vapor deposition further permits investigation of in-plane diffusion and segregation upon passage of current or upon heating to elevated temperatures both with and without encapsulation. To investigate the structural evolution, high-frame rate image acquisition is used in-situ to produce quantitative data from electron micrograph images. Since the structural evolutions and in-homogeneities are expected to be on a sub-visible light wavelength scale, nanoscale, tip-enhanced optical photoluminescence and Raman spectroscopy is used to correlate them with in-situ electron microscopy data. These experiments allow quantitative understanding of how 2D chalcogenides and their heterostructures evolve under physical confinement, high current density and high temperatures, all relevant for high-performance device operation. These experiments allow further assessment of the mechanisms of diffusion and phase transformations processes at these extreme conditions and their impact on optoelectronic performance which provides insight into strategies to engineer both materials and devices for robust and high performance operation.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.

非技术描述：二维（2D）材料一直是强烈的科学研究的主题，因为它们的原子薄质会导致各种各样的新型光学和电子特性。尽管已经进行了许多基本的物理财产调查和设备示范，但了解相关的处理和操作条件（例如结构限制（封装）），高温和大电流流量如何影响其结构和性能，仍然存在很大的知识差距。在现代微电子学中，高性能装置操作中通常会遇到这种情况。因此，了解这些特性对于理解合金和掺杂，异质结和接触形成以及电和热衰竭至关重要。该项目有助于理解这些材料在极端的物理限制和温度下通过直接可视化和光谱分析在电子显微镜内部直接可视化和光谱分析进行的基本热力学过程和转化。然后将这些实验与纳米级光学成像技术结合，以将结构转换与光学和电子性质变化相关联。这些调查推进了我们的基本知识，并有助于制定综合，处理和设备操作注意事项的设计规则。该项目还包括在最前沿材料综合，最先进的显微镜和光谱学的培训研究生的下一代劳动力准备。它还需要通过材料研究科学与工程中心的本科生计划的研究经验来为本科生的劳动力发展。最后，研究成果，特别是互动模型，通过公共讲座，科学外展活动和本科生以及研究生教育室教育将更广泛的公众传播给更广泛的公众。技术描述：该项目的研究目标是研究范德华分层的二维葡萄核化合物系统中的结构相变和扩散现象。近场光谱和原位透射电子显微镜方法的结合，结合了独特的样品制备对预制底物的组合，用于研究结构限制，电流和温度的影响。样品是通过机械剥落和堆叠以及化学蒸气沉积生长制备的。这项工作利用了这些葡萄染剂及其垂直异质结构的原子薄层层的能力，然后将它们封装在惰性和难治层中，例如石墨或氮化硼。此外，通过化学蒸气沉积侧向缝合和生长面内异质结构的能力进一步允许研究平面扩散和隔离，随着电流或加热后，有无封装时加热至升高温度。为了研究结构进化，使用高框架图像采集在原位中用于从电子显微照片图像中产生定量数据。由于预计结构演变和内均匀性将处于可见的光波长尺度上，因此使用纳米级，尖端增强的光学光发光和拉曼光谱法将它们与原位的电子显微镜数据相关联。这些实验可以定量了解2D辣椒剂及其异质结构如何在物理限制，高电流密度和高温下演变，所有这些都与高性能装置的操作有关。这些实验允许进一步评估这些极端条件下的扩散机制和相变过程及其对光电绩效的影响，这些效果可洞悉策略，以设计材料和设备，以实现稳健和高性能操作。该奖项反映了NSF的法规任务，并被认为是通过基金会的智力优点和广泛的范围进行评估，并通过评估来进行评估，并进行了宽广的影响。

项目成果

Direct visualization of out-of-equilibrium structural transformations in atomically thin chalcogenides

• DOI: 10.1038/s41699-020-0150-2
• 发表时间: 2020-02
• 期刊: npj 2D Materials and Applications
• 影响因子: 9.7
• 作者: Pawan Kumar;James P. Horwath;Alexandre C. Foucher;Christopher C. Price;Natalia Acero;V. Shenoy;E. Stach;D. Jariwala

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

• DOI: 10.1038/s41699-020-00178-w
• 发表时间: 2020-12-09
• 期刊: NPJ 2D MATERIALS AND APPLICATIONS
• 影响因子: 9.7
• 作者: Moore, David;Jo, Kiyoung;Glavin, Nicholas R.
• 通讯作者: Glavin, Nicholas R.

Machine Learning-Enabled Design of Point Defects in 2D Materials for Quantum and Neuromorphic Information Processing

• DOI: 10.1021/acsnano.0c05267
• 发表时间: 2020-10-27
• 期刊: ACS NANO
• 影响因子: 17.1
• 作者: Frey, Nathan C.;Akinwande, Deji;Shenoy, Vivek B.
• 通讯作者: Shenoy, Vivek B.

Hybrid exciton-plasmon-polaritons in van der Waals semiconductor gratings

• DOI: 10.1038/s41467-020-17313-2
• 发表时间: 2020-07-15
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Zhang, Huiqin;Abhiraman, Bhaskar;Jariwala, Deep
• 通讯作者: Jariwala, Deep

Giant Gate-Tunability of Complex Refractive Index in Semiconducting Carbon Nanotubes

• DOI: 10.1021/acsphotonics.0c01220
• 发表时间: 2020-09
• 期刊: ACS Photonics
• 影响因子: 7
• 作者: Baokun Song;Fang Liu;Haonan Wang;J. Miao;Yuelin Chen;Pawan Kumar;Huiqin Zhang;Xiwen Liu;Honggang Gu;E. Stach;Xuelei Liang;Shiyuan Liu;Z. Fakhraai;D. Jariwala