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.

非技术摘要提出的研究探讨了纳米级半导体中最基本的过程之一，该过程已知对光电技术有害。了解这种基本机制可能会极大地有助于寻找半导体材料和纳米结构以最大程度地减少螺旋螺旋体的重组，从而提高光电子的效率，例如当今现代生活各个方面使用的光发射二极管和激光。这些应用程序的示例包括交流，信息技术，消费电子产品和照明。尽管从材料/设备和理论角度进行了数十年的研究，但对确定光电子基本基本限制的螺旋钻重组的微观机制知之甚少。为了填补这一关键的知识差距并制定理性策略以提高光电学的效率，PI和合作者将利用其互补专业知识，并执行联合研究计划，以定量探测螺旋螺旋体的重组。美国和以色列的两个主要研究机构之间的合作为年轻科学家体验国际合作提供了绝佳的机会。 PI在扩大研究对本科和中学级别的影响方面有着良好的记录，并将扩大他在Ossining High School的科学研究计划中的作用。在拟议的休假访问中，借助副PI的帮助，PI将在哥伦比亚的研究生和本科级别的完整课程中进一步发展“研究理念和伦理”。技术抽象的重新组合是一个多体性过程，在这种过程中，通过将电子核对配对的非放射性重组置于释放的能量/驱动器上，以有效地转移到第三次驱动器或第三个驱动器。此过程对光电技术有害，范围从传统的发光二极管（LED）和激光器到激光或激子 - 帕顿 - 波利顿冷凝物的量子设备。 PI和合作者将使用两个模型系统定量探测螺旋螺旋体的重组：二维（2D）单层过渡金属二核苷（TMDCS）和异性峰；和2D混合有机无机铅卤化物钙钛矿（LHP）。拟议的研究的目的是通过实验探测螺旋螺旋体重组如何取决于频带结构，电子 - 音波耦合和空间限制，并在定量地了解螺旋散射过程的微观机制。 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被困的电荷）来自螺旋钻的重组以及自旋极化如何影响螺旋螺旋体的重组率。 PI选择两个模型系统，因为它们的电子结构可以在TMDC中的真实和动量空间中控制。它们的带结构对介电筛选，杂界和外部磁场的定向对齐敏感。 LHP被证明是光电子的最具吸引力的材料系统之一，可以生长到2D纳米结构中，从而可以轻松地通过铅卤化物层的数量来控制量子限制。此外，拟议的RASHBA效应是由于强旋转轨道偶联（SOC）和对称局部倒置的破坏可能允许外部电或磁性奖的频带结构来控制频带结构，这反映了NSF的法定任务，并且被认为是值得通过基金会的知识分子和更广泛影响的审查审查的审查标准来通过评估来通过评估来支持的。

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.

Direct determination of momentum-resolved electron transfer in the photoexcited van der Waals heterobilayer WS2/MoS2

• DOI: 10.1103/physrevb.101.201405
• 发表时间: 2020-05-18
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Liu, Fang;Li, Qiuyang;Zhu, Xiaoyang
• 通讯作者: Zhu, Xiaoyang