RUI:Unraveling the Influence of Free Carriers, Phonons and Band Electrons from the Dielectric Function of van der Waals Solids

RUI：从范德华固体的介电函数中揭示自由载流子、声子和带电子的影响

• 批准号: 2004812
• 负责人: Frank Peiris
• 金额: $ 17.9万
• 依托单位: Kenyon College
• 依托单位国家: 美国
• 项目类别: Standard 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=2004812&HistoricalAwards=false
• 关键词: RUI; Unraveling; Influence; Free; Carriers

Non-technical AbstractThe focus of this project is to investigate a new class of materials called 2D van der Walls solids which have interesting properties that can be exploited for making novel electronic and optical devices. A technique known as spectroscopic ellipsometry with a uniquely wide light energy range is used to study the characteristics of a variety of the 2D van der Walls solids. Knowledge gained from this study could advance the development of various devices, such as light emitting diodes, transistors, photovoltaic devices, and lasers. The research work is performed by undergraduate students in a liberal-arts setting, who receive training in materials characterization, preparing them for graduate studies and careers in science and technology. To enhance educational goals, several experimental activities are incorporated into current courses in the curriculum. Additionally, to foster a wider interest in the sciences, several outreach activities for high school students are conducted. Technical AbstractBy combining spectroscopic ellipsometry and reflectivity measurements to cover a wide-spectral range (i.e. 1 meV to 6 eV), this project explores the dielectric function and the complex conductivity of 2D van der Walls materials, particularly transition metal dichalcogenides (TMDCs). Having access to a high spectral range enables the study of the contributions of free carriers, phonons and band electrons (and excitons) of TMDCs. Specifically, the following issues are addressed: (i) the excitonic effects of band transitions; (ii) evolution of transitions with the number of layers; (iii) the mechanism that governs the carrier relaxation time; (iv) the influence of dopants on the transport properties; (v) the significance of electron-phonon coupling on TMDCs; and (vi) quantifying the circular dichroism in TMDCs and explaining their differences. The research work is performed by undergraduate students in a liberal-arts setting. Several experimental activities are injected into current courses such as Condensed Matter Physics, Optics and Advanced Lab. The undergraduate students receive training in materials characterization, optics, and cryogenics, preparing them for graduate studies or careers in STEM-based fields. Additionally, several outreach activities for high school students are conducted in order to foster a wider interest in the sciences.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.

摘要：该项目的重点是研究一类称为二维范德沃尔斯固体的新材料，这种材料具有有趣的性质，可以用于制造新型电子和光学器件。一种被称为光谱椭偏的技术，具有独特的宽光能范围，用于研究各种二维范德沃尔固体的特性。从这项研究中获得的知识可以推动各种器件的发展，如发光二极管、晶体管、光伏器件和激光器。这项研究工作是由本科生在文科环境中进行的，他们接受材料表征方面的培训，为研究生学习和科学技术领域的职业生涯做好准备。为了加强教学目标，一些实验活动被纳入课程的现行课程。此外，为了培养更广泛的科学兴趣，为高中生开展了几项外展活动。技术摘要：本项目通过结合光谱椭偏和反射率测量来覆盖较宽的光谱范围（即1 meV至6 eV），研究了二维范德华斯材料，特别是过渡金属二硫族化合物（TMDCs）的介电函数和复杂电导率。利用高光谱范围可以研究TMDCs的自由载流子、声子和带电子（和激子）的贡献。具体来说，解决了以下问题：(i)带跃迁的激子效应；（ii）过渡随层数的演变；（iii）控制载流子弛豫时间的机制；（iv）掺杂剂对输运性质的影响；(v)电子-声子耦合对TMDCs的意义；（vi）量化TMDCs的圆二色性并解释其差异。这项研究工作是由本科生在文科环境中进行的。一些实验活动被注入到当前的课程中，如凝聚态物理、光学和高级实验室。本科学生接受材料表征、光学和低温学方面的培训，为他们在stem领域的研究生学习或职业生涯做好准备。此外，为了培养更广泛的科学兴趣，还为高中生开展了一些外展活动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Cavity-enhanced linear dichroism in a van der Waals antiferromagnet

• DOI: 10.1038/s41566-022-00970-8
• 发表时间: 2022-02
• 期刊: Nature Photonics
• 影响因子: 35
• 作者: Huiqin Zhang;Z. Ni;C. Stevens;Aofeng Bai;F. Peiris;J. Hendrickson;Liang Wu;D. Jariwala

Probing the growth quality of molecular beam epitaxy-grown Bi2Se3 films via in-situ spectroscopic ellipsometry

• DOI: 10.1016/j.jcrysgro.2022.126714
• 发表时间: 2022-05-20
• 期刊: JOURNAL OF CRYSTAL GROWTH
• 影响因子: 1.8
• 作者: Bai, Aofeng;Hilse, Maria;Peiris, Frank
• 通讯作者: Peiris, Frank