Chasing Polaritons: A Pathway to investigate the optoelectronic properties of van der Waals heterostructures

追逐极化子：研究范德华异质结构光电特性的途径

• 批准号: 443275027
• 负责人: Dr. Patryk Kusch
• 金额: --
• 依托单位: Institut für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/443275027?language=en
• 关键词: Chasing; Polaritons; Pathway; investigate; optoelectronic

In this project we will image exciton polaritons of 2D van der Waals heterostructures to observe interlayer excitons and optical moiré patterns using a wavelength-tunable near-field scanning optical microscope with visible laser excitation, which was first build by us. Van-der-Waals heterostructures of transition-metal dichalcogenides (TMDs) show peculiar excitations that correspond to bound states between an electron in one and a hole in the other layer. These interlayer excitons and their trions have been predicted to show superior lifetime and propagation length, because of suppressed radiative decay. We will image the propagation of the interlayer exciton and trion polaritons in real space by recording near-field interference patterns with nanoscale resolution. The second remarkable feature of 2D heterostructures are moiré patterns that form due to the stacking of two misaligned lattices (orientation, lattice constant). We want to image the change in local atomic configuration by recording near-field images of the absorption coefficient that is highly sensitive to small changes in the electronic potential. By tuning the laser into resonance with the transitions in the moiré lattice we will observe the distortion of the polariton propagation due to band bending and localized optical quantum dots within the superlattice. Our experiments will be performed for various materials combinations and relative monolayer orientation. Combining nanoscale microscopy with far-field and near-field spectroscopy we will extract excitation energies, lifetimes, propagation length, and the coupling strength of light-matter interaction. We will develop techniques for characterizing TMD van-der-Waals heterostructures using optical spectroscopy. Our project will benefit from strong collaborations within the SPP 2D Materials for sample preparation, characterization, and theoretical modeling.

在本计画中，我们将利用我们所建立的波长可调近场扫描光学显微镜，利用可见光激发，对二维货车德瓦耳斯异质结构的激子极化激元进行成像，观察层间激子与光学云纹图案。过渡金属二硫属化物（TMD）的范德华异质结构显示出与一层中的电子和另一层中的空穴之间的束缚态相对应的特殊激发。这些层间激子和它们的trions已经被预测显示出优越的上级寿命和传播长度，因为抑制了辐射衰减。我们将利用奈米尺度的近场干涉图样，来记录层间激子与激子极化激元在真实的空间中的传播。二维异质结构的第二个显著特征是由于两个未对准的晶格（取向，晶格常数）的堆叠而形成的莫尔图案。我们希望通过记录对电子势的微小变化高度敏感的吸收系数的近场图像来成像局部原子构型的变化。通过将激光调谐到与莫尔晶格中的跃迁共振，我们将观察到由于超晶格内的能带弯曲和局域化的光学量子点而导致的极化激元传播的失真。我们的实验将针对各种材料组合和相对单层取向进行。结合纳米尺度显微镜与远场和近场光谱，我们将提取激发能，寿命，传播长度，光-物质相互作用的耦合强度。我们将开发技术，利用光学光谱学来表征TMD范德华异质结构。我们的项目将受益于SPP 2D Materials在样品制备、表征和理论建模方面的强大合作。