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科学新发现:光物质相互作用可改善电子和光电器件

2018-12-13

Rensselaer Polytechnic Institute的化学和生物工程助理教授Sufei Shi在Nature Communications上发表的一篇论文,增加了我们对光与原子级薄半导体如何相互作用的理解,并创造了独特的激子复合粒子,多个电子和强烈结合在一起的空穴。

这些粒子具有新的量子自由度,称为“谷旋转”。

“谷旋转”类似于电子自旋,其已被广泛用于诸如硬盘驱动器的信息存储中,并且也是量子计算的有希望的候选者。

这篇题为“揭示BN封装的WSe2中的双激子和三价激子复合物”的论文发表在2018年9月13日的Nature Communications上。

这项研究的结果可能导致电子和光电器件的新应用,如太阳能收集,新型激光和量子传感。

Shi的研究主要集中在低维量子材料及其量子效应,特别关注具有强光物质相互作用的材料。

这些材料包括石墨烯,过渡金属二硫化物(TMD),例如二硒化钨(WSe2)和拓扑绝缘体。

TMD代表了一类具有优异光学和光电特性的原子级薄半导体。二维单层TMD上的光学激发将产生称为激子的强结合电子 - 空穴对,而不是像传统的体半导体那样自由地移动电子和空穴。

这是由于单层TMD中的巨大结合能,比传统半导体大几个数量级。结果,激子可以在室温下存活,因此可以用于激子器件的应用。

随着激子密度的增加,更多的电子和空穴结合在一起,形成四粒子甚至五粒子的激子复合物。

对多粒子激子复合物的理解不仅使得对二维光物质相互作用有了基本的了解,而且还导致了新的应用,因为多粒子激子复合物保持了“谷旋转”特性。激子。

然而,尽管最近对TMD中的激子和π反应的理解有所发展,但Shi说,对于结合双能的能量的明确测量仍然是难以捉摸的。

“现在,我们第一次揭示了真正的双原子状态,一种独特的四粒子复合物,对光响应,”施说。

“我们还揭示了带电biexciton的性质,这是一种五粒子复合物。”

在Rensselaer,Shi的团队已经开发出一种方法来构建极其干净的样品,以揭示这种独特的光物质相互作用。

该器件是通过将多个原子级薄材料堆叠在一起而构建的,包括石墨烯,氮化硼(BN)和WSe2,通过范德瓦尔斯(vdW)相互作用,代表了二维材料的最先进制造技术。

这项工作是与佛罗里达州塔拉哈西国家高磁场实验室和日本国家材料科学研究所的研究人员以及物理系应用物理系Kodosky Constellation教授张百柏合作完成的。伦斯勒的天文学和天文学,他的工作在发展对biexcon的理论理解中发挥了关键作用。

Shi说,这项研究的结果可能会导致强大的多粒子光学物理学,并说明基于二维半导体的新型应用。

施已获得空军科学研究办公室的资助。张得到了能源部科学办公室的支持。该研究最近也出现在Nature Nanotechnology中。

Shi于2015年7月加入伦斯勒的化学与生物工程系。他获得了自己的学士学位。在南京大学,他的博士学位在康奈尔大学。然后,他在加州大学伯克利分校获得了博士后奖学金。 Shi还与Rensselaer的电气,计算机和系统工程系联合任命。

 

-------------------------------------英文版(原文)--------------------------------------------
Light-matter Interaction Improves Electronic and Optoelectronic Devices
来源:ENERGYMETALNEWS


A paper published in Nature Communications by Sufei Shi, assistant professor of chemical and biological engineering at Rensselaer Polytechnic Institute, increases our understanding of how light interacts with atomically thin semiconductors and creates unique excitonic complex particles, multiple electrons, and holes strongly bound together.

These particles possess a new quantum degree of freedom, called “valley spin.”

The “valley spin” is similar to the spin of electrons, which has been extensively used in information storage such as hard drives and is also a promising candidate for quantum computing.

The paper, titled “Revealing the biexciton and trion-exciton complexes in BN encapsulated WSe2,” was published in the Sept. 13, 2018, edition of Nature Communications.

Results of this research could lead to novel applications in electronic and optoelectronic devices, such as solar energy harvesting, new types of lasers, and quantum sensing.

Shi’s research focuses on low dimensional quantum materials and their quantum effects, with a particular interest in materials with strong light-matter interactions.

These materials include graphene, transitional metal dichacogenides (TMDs), such as tungsten diselenide (WSe2), and topological insulators.

TMDs represent a new class of atomically thin semiconductors with superior optical and optoelectronic properties. Optical excitation on the two-dimensional single-layer TMDs will generate a strongly bound electron-hole pair called an exciton, instead of freely moving electrons and holes as in traditional bulk semiconductors.

This is due to the giant binding energy in monolayer TMDs, which is orders of magnitude larger than that of conventional semiconductors. As a result, the exciton can survive at room temperature and can thus be used for application of excitonic devices.

As the density of the exciton increases, more electrons and holes pair together, forming four-particle and even five-particle excitonic complexes.

An understanding of the many-particle excitonic complexes not only gives rise to a fundamental understanding of the light-matter interaction in two dimensions, it also leads to novel applications, since the many-particle excitonic complexes maintain the “valley spin” properties better than the exciton.

However, despite recent developments in the understanding of excitons and trions in TMDs, says Shi, an unambiguous measure of the biexciton-binding energy has remained elusive.

“Now, for the first time, we have revealed the true biexciton state, a unique four-particle complex responding to light,” says Shi.

“We also revealed the nature of the charged biexciton, a five-particle complex.”

At Rensselaer, Shi’s team has developed a way to build an extremely clean sample to reveal this unique light-matter interaction.

The device was built by stacking multiple atomically thin materials together, including graphene, boron nitride (BN), and WSe2, through van der Waals (vdW) interaction, representing the state-of-the-art fabrication technique of two-dimensional materials.

This work was performed in collaboration with the National High Magnetic Field Laboratory in Tallahasee, Florida, and researchers at the National Institute for Materials Science in Japan, as well as with Shengbai Zhang, the Kodosky Constellation Professor in the Department of Physics, Applied Physics, and Astronomy at Rensselaer, whose work played a critical role in developing a theoretical understanding of the biexciton.

The results of this research could potentially lead to robust many-particle optical physics, and illustrate possible novel applications based on 2D semiconductors, Shi says.

Shi has received funding from the Air Force Office of Scientific Research. Zhang was supported by the Department of Energy, Office of Science. The research also was recently featured in Nature Nanotechnology.

Shi joined the Department of Chemical and Biological Engineering at Rensselaer in July 2015. He earned his B.S. at Nanjing University, and his Ph.D. at Cornell University. He then held a postdoctoral fellowship at UC Berkeley. Shi also holds a joint appointment with the Department of Electrical, Computer, and Systems Engineering at Rensselaer.

(来源:明日科技



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