Role of weak interlayer coupling in ultrafast exciton-exciton annihilation in two-dimensional rhenium dichalcogenides
Role of weak interlayer coupling in ultrafast exciton-exciton annihilation in two-dimensional rhenium dichalcogenides
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DOI：
10.1103/physrevb.101.174309
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发表时间：
2020-05
影响因子：
3.7
通讯作者：
Sangwan Sim;Doeon Lee;Jekwan Lee;Myungjun Cha;Soonyoung Cha;Wonhyeok Heo;Sungjun Cho;W. Shim;Kyusang Lee;Jinkyoung Yoo;R. Prasankumar;Hyunyong Choi;M. Jo
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文献类型：
--
作者：
Sangwan Sim;Doeon Lee;Jekwan Lee;Myungjun Cha;Soonyoung Cha;Wonhyeok Heo;Sungjun Cho;W. Shim;Kyusang Lee;Jinkyoung Yoo;R. Prasankumar;Hyunyong Choi;M. Jo
激子之间的强相互作用是二维 (2D) 半导体的一个特征，决定了重要的激子特性，例如激子寿命、相干性和光子发射效率。二硫化铼（）是二维过渡金属二硫属化物（TMD）家族的一员，由于其独特的激子表现出优异的偏振选择性和相干性特征，最近引起了极大的关注。然而，仍然缺乏对激子-激子相互作用的深入理解。在这里，我们使用超快泵浦探针光谱来研究单层 (1L)、双层 (2L) 和三层中的激子-激子相互作用。我们直接测量激子-激子湮灭的速率，激子之间具有代表性的俄歇型相互作用。正如在其他 2D TMD 中观察到的那样，它随着层数的增加而减小。然而，虽然其他 TMD 在 1L 和 2L 之间表现出激子-激子湮灭的急剧减弱，但在 1L 和 2L 之间没有观察到这种行为。我们将这种独特的特征归因于相对较弱的层间耦合，当厚度变化时，层间耦合阻止了电子结构的实质性变化。这项工作不仅强调了其独特的激子性质，而且还为二维系统中激子-激子相互作用的厚度依赖性提供了新的见解。
Strong interactions between excitons are a characteristic feature of two-dimensional (2D) semiconductors, determining important excitonic properties, such as exciton lifetime, coherence, and photon-emission efficiency. Rhenium disulfide (), a member of the 2D transition-metal dichalcogenide (TMD) family, has recently attracted great attention due to its unique excitons that exhibit excellent polarization selectivity and coherence features. However, an in-depth understanding of exciton-exciton interactions inis still lacking. Here we used ultrafast pump-probe spectroscopy to study exciton-exciton interactions in monolayer (1L), bilayer (2L), and triple layer. We directly measure the rate of exciton-exciton annihilation, a representative Auger-type interaction between excitons. It decreases with increasing layer number, as observed in other 2D TMDs. However, while other TMDs exhibit a sharp weakening of exciton-exciton annihilation between 1L and 2L, such behavior was not observed in. We attribute this distinct feature into the relatively weak interlayer coupling, which prohibits a substantial change in the electronic structure when the thickness varies. This work not only highlights the unique excitonic properties ofbut also provides novel insight into the thickness dependence of exciton-exciton interactions in 2D systems.