Investigations of low-dimensional emitter system by dynamic strain platform

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An, Zhao: Investigations of low-dimensional emitter system by dynamic strain platform. Hannover : Gottfried Wilhelm Leibniz Universität, Diss., 2023, 121 S., DOI: https://doi.org/10.15488/13603

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Abstract: 
Two-dimensional transitional metal dichalcogenides (2D TMDs) and zero-dimensional quantum dots (QDs) are among the most representative low-dimensional emitter systems, with one or three dimensions on nano-scale. Both of them exhibit potential for (quantum) optical applications. Analog to the electric field and magnetic field, strain is a powerful probe to detect the physics of the emitter systems. The reduced dimension renders strain tuning more applicable to deepen the understanding and tune their properties. Previous researches demonstrate that strain can change the distance of particles or/and the symmetry. Based on this, we conduct some investigations: first, we detect the responses of monolayer WSe2 to biaxial in-plane strain. Generally, all the helicities of excitons and trions are related to the scattering process. In our observation, the decreases of exciton circular helicities in WSe2 and MoSe2 are associated with their e-h exchange interactions. The helicity of trion in MoSe2 is almost intact, and a phenomenological rate equation model is developed to describe the decrease of trions in WSe2, which agrees with our observation well. Our findings provide a new strategy to tune the read-in/read-out in TMDs-based memory devices. Second, we focus on the responses of WSe2 to uniaxial strain. We identify fine structures of neutral exciton in polarization-dependent photoluminescence spectroscopy. The nonlinear evolutions, in terms of amplitude and phase, with an active uniaxial strain are interpreted by the interaction of wavefunction with strain. Though these two bulk strain-tuning platforms hold the potential for sophisticated emitter systems, a more versatile strain-tuning platform is needed. In the last section of this work, a 2-leg MEMS strain-tuning platform is fabricated and then integrated with a QDs-embedded membrane. We resolve the position-dependent anisotropic strain on the strain-tuning platform and compare the opposite responses of positive and negative trions to the same strain. Our observation agrees well with the previous pseudo-potential/configuration interaction calculations. Notably, the 2-leg strain platform applies to 2D TMDs.These findings act as some helpful attempts to deepen the understanding of low-dimensional emitter systems. In some ongoing work, we get a prototype as a more versatile strain-tuning platform. We envision this platform can add a degree of freedom for the integrated photonic circuits.
License of this version: Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Document Type: DoctoralThesis
Publishing status: publishedVersion
Issue Date: 2023
Appears in Collections:Fakultät für Mathematik und Physik
Dissertationen

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pos. country downloads
total perc.
1 image of flag of Germany Germany 88 38.10%
2 image of flag of United States United States 35 15.15%
3 image of flag of China China 30 12.99%
4 image of flag of Hong Kong Hong Kong 14 6.06%
5 image of flag of Korea, Republic of Korea, Republic of 13 5.63%
6 image of flag of No geo information available No geo information available 6 2.60%
7 image of flag of Spain Spain 5 2.16%
8 image of flag of Greece Greece 4 1.73%
9 image of flag of Italy Italy 3 1.30%
10 image of flag of Brazil Brazil 3 1.30%
    other countries 30 12.99%

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