Goldstein Thomas, Wu Yueh-Chun, Chen Shao-Yu, Taniguchi Takashi, Watanabe Kenji, Varga Kalman, Yan Jun
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
J Chem Phys. 2020 Aug 21;153(7):071101. doi: 10.1063/5.0013092.
Monolayer transition metal dichalcogenide semiconductors, with versatile experimentally accessible exciton species, offer an interesting platform for investigating the interaction between excitons and a Fermi sea of charges. Using hexagonal boron nitride encapsulated monolayer MoSe, we study the impact of charge density tuning on the A and B series of exciton Rydberg states, including A:1s, A:2s, B:1s, and B:2s. The doping dependence of the A:2s state provides an opportunity to examine such interactions with greatly reduced exciton binding energy and more spatially diffuse structures, and we found that the impact of the Fermi sea becomes much more dramatic compared to the A:1s state. Using photoluminescence upconversion, we verify that the B:2s exciton state displays similar behavior when interacting with the Fermi sea despite being well above the bare bandgap in energy. Photoluminescence and reflection spectra of the A:1s state show clear evidence that the interaction of the exciton with a Fermi sea is best described by the exciton-polaron model, rather than a trion model. Our experimental results demonstrate that overall features of charge interaction are quite generic and highly robust, offering key insights into the dressed many body states in a Fermi sea.
单层过渡金属二硫族化合物半导体具有多种实验上可获取的激子种类，为研究激子与费米电荷海之间的相互作用提供了一个有趣的平台。利用六方氮化硼封装的单层MoSe₂，我们研究了电荷密度调谐对激子里德堡态的A系列和B系列的影响，包括A:1s、A:2s、B:1s和B:2s。A:2s态的掺杂依赖性提供了一个机会，以研究具有大幅降低的激子结合能和更空间弥散结构的此类相互作用，并且我们发现与A:1s态相比，费米海的影响变得更加显著。利用光致发光上转换，我们证实B:2s激子态在与费米海相互作用时表现出类似行为，尽管其能量远高于裸带隙。A:1s态的光致发光和反射光谱清楚地表明，激子与费米海的相互作用最好用激子极化子模型来描述，而不是用三重子模型。我们的实验结果表明，电荷相互作用的总体特征相当普遍且高度稳健，为费米海中的修饰多体态提供了关键见解。
