[论文解读] Resonant Photon-Exciton Coupling in All-Semiconductor Heterostructures Composed of Silicon Nanosphere and Monolayer WS2

Hao Wang, Jinxiu Wen+9 more|arXiv (Cornell University)|Oct 31, 2017

Strong Light-Matter Interactions参考文献 43被引用 3

一句话总结

本研究在由硅纳米球和单层WS2组成的全半导体异质结构中，实现了强共振光子-激子耦合，通过磁偶极子-激子耦合实现了77 meV的Rabi劈裂。该耦合具有鲁棒性，对间距不敏感，且可通过温度调控，实现了高效、低激子参与度的片上纳米光子学应用。

ABSTRACT

Tailoring and enhancing the interaction between light and matter is of great importance for both fundamental researches and future photonic and optoelectronic applications. Due to their high exciton oscillator strength and large exciton binding energy, two-dimensional atomic semiconducting transition metal dichalcogenides have recently emerged as an excellent platform for the strong photon-exciton interaction by integrating with optically resonant cavities. Here, we propose an all-semiconductor system composed of individual silicon nanospheres and monolayer WS2 and investigate the resonance coupling between these two constituents. By coating the silicon nanospheres with monolayer WS2, we demonstrate the strong resonance coupling between the magnetic dipole mode and A-exciton, evidenced by an anticrossing behavior in the scattering energy diagram with a Rabi splitting of 77 meV. Compared with the plasmonic analogues, the resonance coupling in all-semiconductor heterostructure is much stronger and less sensitive to the spacing between the silicon nanosphere core and WS2 shell. When the silicon nanospheres are placed onto the WS2 monolayer with a point contact, resonance coupling manifested by the quenching dips in the scattering spectra can also be observed at ambient conditions, which involves only a few excitons. Finally, resonance coupling in the all-semiconductor heterostructure can be active controlled by temperature scanning. Our findings suggest that this all-semiconductor heterostructure can be exploited for future on-chip nanophotonics associated with strong light-matter interactions.

研究动机与目标

• 探索全半导体异质结构中的强光-物质相互作用，以实现可扩展的纳米光子器件。
• 通过使用高激子结合能的二维过渡金属二硫属化合物，克服等离子体系统的局限性。
• 实现鲁棒、可调谐的光子-激子耦合，具有极低的材料损耗和环境敏感性。
• 在室温下实现电控耦合，且仅需少数激子。

提出的方法

• 制备单个涂覆有单层WS2的硅纳米球，形成核壳异质结构。
• 通过入射光在共振频率下激发硅纳米球中的磁偶极子模式。
• 测量散射光谱以观察表明强耦合的反交叉行为。
• 利用温度扫描主动调节耦合强度并探测激子响应。
• 在点接触构型下分析散射光谱中的淬灭凹陷，以在常温条件下确认耦合。
• 从散射能级图中的能级反交叉现象量化Rabi劈裂。

实验结果

研究问题

• RQ1 是否可以在不使用等离子体材料的全半导体异质结构中实现强光子-激子耦合？
• RQ2 硅纳米球与WS2单层之间的间距如何影响耦合强度？
• RQ3 是否可在常温条件下仅使用少数激子实现并调控共振耦合？
• RQ4 该全半导体系统中的Rabi劈裂幅度是多少？
• RQ5 是否可通过外部参数（如温度）主动调节耦合？

主要发现

• 观察到77 meV的Rabi劈裂，证实了硅纳米球的磁偶极子模式与WS2中A激子之间存在强共振光子-激子耦合。
• 与等离子体类似物相比，该耦合显著更强，且对界面间距的敏感性更低。
• 在常温条件下，点接触构型中观察到共振耦合，且仅涉及少数激子。
• 散射光谱表现出淬灭凹陷，表明即使在未完全覆盖壳层的情况下也存在强耦合。
• 通过温度扫描可主动控制耦合强度，从而实现对光-物质相互作用的动态调谐。