NSF/DMR-BSF: Auger Recombination in Two-Dimensional Quantum Confined Semiconductors

NSF/DMR-BSF：二维量子限制半导体中的俄歇复合

• 批准号: 1809680
• 负责人: Xiaoyang Zhu
• 金额: $ 49.86万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809680&HistoricalAwards=false
• 关键词: NSF; DMR; BSF; Auger; Recombination

NON-TECHNICAL ABSTRACTThe proposed research probes one of the most fundamental processes in nanoscale semiconductors, a process known to be detrimental to optoelectronic technologies. Understanding this fundamental mechanism may greatly aid the search for semiconductor materials and nanostructures to minimize Auger recombination, thus increasing the efficiency of optoelectronics, such as light emitting diodes and lasers used in all aspects of modern life today. Examples of these applications include, among others, communication, information technology, consumer electronics, and lighting. Despite decades of research from both materials/device and theoretical perspectives, little is known about the microscopic mechanisms of Auger recombination that determine fundamental limits of optoelectronics. To fill this critical knowledge gap and formulate rational strategies to increase the efficiency of optoelectronics, the PI and collaborator will take advantage of their complementary expertise and carry out a joint research program to quantitatively probe Auger recombination. The collaboration between two premier research institutions in the US and Israel provides an excellent opportunity for young scientists to experience international collaboration. The PI has had a strong track record of extending the impact of research to undergraduate and secondary school levels and will expand his role in the Science Research Program at Ossining High School. With the help of the co-PI during a proposed sabbatical visit, the PI will further develop "Research Philosophy and Ethics" to a full course at the graduate and undergraduate level at Columbia.TECHNICAL ABSTRACTAuger recombination is a many-body process in which the non-radiative recombination of an electron-hole pair occurs efficiently by transferring the released energy/momentum to a third charge carrier or an exciton. This process is detrimental to optoelectronic technologies, ranging from conventional light emitting diodes (LEDs) and lasers to quantum devices of exciton or exciton-polariton condensates. The PI and collaborator will quantitatively probe Auger recombination using two model systems: two dimensional (2D) monolayer transition metal dichalcogenides (TMDCs) and heterojunctions; and 2D hybrid organic-inorganic lead halide perovskites (LHPs). The objective of the proposed research is to experimentally probe how Auger recombination depends on the band structure, electron-phonon coupling, and spatial confinement, and to quantitatively understand the microscopic mechanisms underlying the Auger scattering process. Whenever possible, the PIs will implement the most direct experimental probes, e.g., using femtosecond photoemission spectroscopy to directly detect Auger electrons as they scatter into particular energy and momentum spaces, absorption/emission spectroscopies to determine Auger recombination rates as functions of spatial confinement and momentum engineering, and magneto-optical spectroscopies to identify and quantify charged products (polarons, trions, and trapped charges) from Auger recombination and how spin polarization can influence Auger recombination rates. The PIs choose the two model systems because their electronic structures can be controlled in real and momentum spaces in TMDCs. Their band structures are sensitive to dielectric screening, to orientation alignment in heterojunctions, and to external magnetic field. The LHPs, demonstrated as one of the most attractive material systems for optoelectronics, can be grown into 2D nanostructured, allowing easy control of quantum confinement by the number of lead halide layers. Moreover, the proposed Rashba effect due to strong spin-orbital-coupling (SOC) and breaking of local inversion of symmetry may allow the control of band structure by external electric or magneticThis 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.

非技术摘要拟议中的研究探测纳米半导体中最基本的过程之一，一个已知的过程是有害的光电技术。理解这一基本机制可能会极大地帮助寻找半导体材料和纳米结构，以最大限度地减少俄歇复合，从而提高光电子学的效率，例如用于现代生活各个方面的发光二极管和激光器。这些应用的示例包括通信、信息技术、消费电子和照明等。尽管从材料/器件和理论角度进行了数十年的研究，但对决定光电子学基本极限的俄歇复合的微观机制知之甚少。为了填补这一关键的知识空白，并制定合理的策略来提高光电子学的效率，PI和合作者将利用他们互补的专业知识，开展一项联合研究计划，以定量探测俄歇复合。美国和以色列两个主要研究机构之间的合作为年轻科学家提供了一个体验国际合作的绝佳机会。PI有一个很好的记录，将研究的影响扩展到本科和中学水平，并将扩大他在奥西宁高中科学研究计划中的作用。在一次建议的休假访问期间，在合作PI的帮助下，PI将进一步发展“研究哲学和伦理学”，使其成为哥伦比亚大学研究生和本科生的一门完整课程。技术摘要俄歇复合是一种多体过程，其中电子空穴对的非辐射复合通过将释放的能量/动量转移到第三电荷载流子或激子而有效地发生。这个过程对光电技术是有害的，从传统的发光二极管（LED）和激光器到激子或激子-极化激子凝聚物的量子器件。PI和合作者将使用两个模型系统定量探测俄歇复合：二维（2D）单层过渡金属二硫属化物（TMDC）和异质结;以及2D混合有机-无机卤化铅钙钛矿（LHP）。拟议的研究的目的是实验探测俄歇复合如何取决于能带结构，电子-声子耦合和空间限制，并定量地了解俄歇散射过程的微观机制。在可能的情况下，PI将实施最直接的实验探测，例如， 使用飞秒光电发射光谱法直接检测俄歇电子，因为它们散射到特定的能量和动量空间中，使用吸收/发射光谱法确定俄歇复合速率作为空间限制和动量工程的函数，使用磁光光谱法识别和量化来自俄歇复合的带电产物（极化子、三重子和捕获电荷）以及自旋极化如何影响俄歇复合速率。PI选择这两个模型系统是因为它们的电子结构可以在TMDCs的真实的和动量空间中控制。它们的能带结构对介电屏蔽、异质结中的取向对准和外部磁场敏感。LHP被证明是光电子学中最有吸引力的材料系统之一，可以生长成2D纳米结构，从而可以通过卤化铅层的数量轻松控制量子限制。此外，由于强自旋轨道耦合（SOC）和打破局部对称反转而提出的Rashba效应可能允许通过外部电或磁控制能带结构。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审查标准进行评估，被认为值得支持。

项目成果

Direct Determination of Band-Gap Renormalization in the Photoexcited Monolayer MoS2

• DOI: 10.1103/physrevlett.122.246803
• 发表时间: 2019-06-21
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Liu, Fang;Ziffer, Mark E.;Zhu, Xiaoyang
• 通讯作者: Zhu, Xiaoyang

Optical parametric amplification by monolayer transition metal dichalcogenides

• DOI: 10.1038/s41566-020-00728-0
• 发表时间: 2020-12-21
• 期刊: NATURE PHOTONICS
• 影响因子: 35
• 作者: Trovatello, Chiara;Marini, Andrea;Cerullo, Giulio
• 通讯作者: Cerullo, Giulio

Optical generation of high carrier densities in 2D semiconductor heterobilayers

• DOI: 10.1126/sciadv.aax0145
• 发表时间: 2019-09
• 期刊: Science Advances
• 影响因子: 13.6
• 作者: Jue Wang;J. Ardelean;Yusong Bai;A. Steinhoff;M. Florian;F. Jahnke;Xiaodong Xu;M. Kira;J. Hone;X. Zhu

Disassembling 2D van der Waals crystals into macroscopic monolayers and reassembling into artificial lattices

• DOI: 10.1126/science.aba1416
• 发表时间: 2020-02-21
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Liu, Fang;Wu, Wenjing;Zhu, X. -Y.
• 通讯作者: Zhu, X. -Y.

Diffusivity Reveals Three Distinct Phases of Interlayer Excitons in MoSe2/WSe2 Heterobilayers

• DOI: 10.1103/physrevlett.126.106804
• 发表时间: 2021-03-11
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Wang, Jue;Shi, Qianhui;Zhu, X-Y
• 通讯作者: Zhu, X-Y