Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors

doi:10.1126/science.aba1029

GSTDTAP > 气候变化

DOI	10.1126/science.aba1029
	Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors
	Julien Madéo; Michael K. L. Man; Chakradhar Sahoo; Marshall Campbell; Vivek Pareek; E. Laine Wong; Abdullah Al-Mahboob; Nicholas S. Chan; Arka Karmakar; Bala Murali Krishna Mariserla; Xiaoqin Li; Tony F. Heinz; Ting Cao; Keshav M. Dani
	2020-12-04
发表期刊	Science
出版年	2020
英文摘要	Excitons, electron-hole pairs held together by Coulomb attraction, can be generated in semiconductors under excitation and greatly influence the material's optoelectronic properties. Although bright excitons are optically active, their dark-state cousins have been more difficult to detect. They do, however, affect the optoelectronic properties through their interaction with light and bright excitons. Madéo et al. developed a pump-probe photoemission technique that is used reveal the spatial, temporal, and spectral dynamics of excitons (see the Perspective by Na and Ye). Demonstrated in two-dimensional monolayer films of tungsten diselenide, the technique could also be applicable to other semiconductor systems hosting excitonic excitations. Science , this issue p. [1199][1]; see also p. [1166][2] Resolving momentum degrees of freedom of excitons, which are electron-hole pairs bound by the Coulomb attraction in a photoexcited semiconductor, has remained an elusive goal for decades. In atomically thin semiconductors, such a capability could probe the momentum-forbidden dark excitons, which critically affect proposed opto-electronic technologies but are not directly accessible using optical techniques. Here, we probed the momentum state of excitons in a tungsten diselenide monolayer by photoemitting their constituent electrons and resolving them in time, momentum, and energy. We obtained a direct visual of the momentum-forbidden dark excitons and studied their properties, including their near degeneracy with bright excitons and their formation pathways in the energy-momentum landscape. These dark excitons dominated the excited-state distribution, a surprising finding that highlights their importance in atomically thin semiconductors. [1]: /lookup/doi/10.1126/science.aba1029 [2]: /lookup/doi/10.1126/science.abf0371
领域	气候变化 ; 资源环境
URL	查看原文
引用统计	被引频次：138[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/305836
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Julien Madéo,Michael K. L. Man,Chakradhar Sahoo,et al. Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors[J]. Science,2020.
APA	Julien Madéo.,Michael K. L. Man.,Chakradhar Sahoo.,Marshall Campbell.,Vivek Pareek.,...&Keshav M. Dani.(2020).Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors.Science.
MLA	Julien Madéo,et al."Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors".Science (2020).