EXCITON PHASE TRANSITION IN ATOMICALLY THIN 2D SEMICONDUCTORS

原子薄二维半导体中的激子相变

• 批准号: 1709934
• 负责人: Kenan Gundogdu
• 金额: $ 44.52万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709934&HistoricalAwards=false
• 关键词: EXCITON; PHASE; TRANSITION; ATOMICALLY; THIN

Nontechnical Abstract: Optical excitations in semiconductors create electron and hole pairs. These quasiparticles are responsible for optoelectronic behavior of materials used in many device applications including, photovoltaics, light emitting diodes and light detectors. These electron and hole quasiparticles, similar to particles in ambient, can go through phase transitions from noninteracting gas to condensed liquid phase at high enough densities and low temperatures. The condensed quasiparticle state exhibits very different electronic properties compared to dilute phase. However so far the studies involving the electron-hole condensation are limited to very low temperatures and high laser excitation densities in limited group of material systems. This project focuses on study of these condensed electron-hole states in atomically thin semiconductors at high temperatures. The educational component of the research involves recruiting high school students specifically from underrepresented communities to the labs. Technical AbstractAtomically thin 2D transition metal dichalcogenides (TMDC) provide a remarkable excitonic system with a large exciton binding energy, more than an order of magnitude larger than typical semiconductor materials. These materials can provide unprecedented opportunities for the studies of quantum many-body physics at elevated temperatures. It has been known that excitons at high enough densities condense into electron-hole plasma and then into a liquid. But in general this gas to liquid phase transition takes place at cryo-temperatures. Here the proposed work aims to study the phase transition of excitons in 2D TMDC materials into a state of electron-hole liquid (EHL) at room temperature and above. This exciton condensation is a quantum mechanical analogue of the classical gas condensation into a liquid droplet. This work will pursue a thorough understanding of the exciton condensation in 2D TMDC materials.

非技术摘要：半导体中的光激发产生电子和空穴对。这些准粒子负责许多器件应用中使用的材料的光电行为，包括光电器件、发光二极管和光探测器。这些电子和空穴准粒子，类似于环境中的粒子，可以在足够高的密度和低温下经历从非相互作用的气体到凝聚液相的相变。凝聚态的准粒子态与稀相态的准粒子态具有非常不同的电子性质。然而，迄今为止，涉及电子空穴凝聚的研究仅限于极低温度和高激光激发密度的有限组材料系统。该项目的重点是研究高温下原子级薄半导体中这些凝聚的电子空穴态。这项研究的教育部分包括招募高中生，特别是来自代表性不足的社区的学生到实验室。原子薄的2D过渡金属二硫属化物（TMDC）提供了具有大激子结合能的显著的激子系统，比典型的半导体材料大一个数量级以上。这些材料可以为高温下的量子多体物理研究提供前所未有的机会。众所周知，密度足够高的激子会凝结成电子-空穴等离子体，然后凝结成液体。但一般来说，这种气体到液体的相变发生在低温下。在这里，拟议的工作旨在研究在室温及以上的2D TMDC材料中的激子的相变到电子空穴液体（EHL）状态。这种激子凝聚是经典气体凝聚成液滴的量子力学模拟。这项工作将追求在2D TMDC材料的激子凝聚的透彻理解。

项目成果

Fermi liquid theory sheds light on hot electron-hole liquid in 1L−MoS2

费米液体理论揭示了 1L·MoS2 中的热电子空穴液体

• DOI: 10.1103/physrevb.103.075416
• 发表时间: 2021
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Wilmington, R. L.;Ardekani, H.;Rustagi, A.;Bataller, A.;Kemper, A. F.;Younts, R. A.;Gundogdu, K.
• 通讯作者: Gundogdu, K.

Near Band‐Edge Optical Excitation Leading to Catastrophic Ionization and Electron–Hole Liquid in Room‐Temperature Monolayer MoS 2

近带边光学激发导致灾难性电离和室温单层 MoS 2 中的电子空穴液体

• DOI: 10.1002/pssb.201900223
• 发表时间: 2019
• 期刊: physica status solidi (b
• 作者: Younts, Robert;Bataller, Alexander;Ardekani, Hossein;Yu, Yiling;Cao, Linyou;Gundogdu, Kenan
• 通讯作者: Gundogdu, Kenan