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Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures
Stanislav Fillipov1, Yuttapoom Puttisong1, Yuqing Huang1
1†Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden.
ACS Nano
|May 13, 2015
Summary
Fine-structure splitting (FSS) in quantum dots is tunable by geometric arrangement, crucial for quantum information and spintronics. Different quantum-dot molecular structures (QMSs) show varying FSS, enabling control over optical polarization for advanced devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Information Science
Background:
- Fine-structure splitting (FSS) of excitons in semiconductor nanostructures is critical for quantum information technology and spintronics.
- Exciton FSS influences photon entanglement and polarization conversion between electron spins and photons.
- Understanding FSS in various quantum-dot molecular structures (QMSs) is essential for device applications.
Purpose of the Study:
- To investigate the exciton fine-structure splitting (FSS) in different self-organized lateral InAs/GaAs quantum-dot molecular structures (QMSs).
- To correlate FSS trends with geometric arrangements in double quantum dots (DQDs), quantum-dot clusters (QCs), and quantum rings (QRs).
- To explore the potential for tuning FSS and optical polarization for quantum and spintronic applications.
Main Methods:
- Utilized polarization-resolved microphotoluminescence (μPL) spectroscopy to analyze exciton FSS.
- Studied self-organized lateral InAs/GaAs QMSs, including DQDs, QCs, and QRs.
- Analyzed the relationship between geometric arrangement, FSS, and optical polarization directions.
Main Results:
- Observed a clear trend in FSS: large in DQDs, smaller in QCs and QRs, dependent on geometric arrangement.
- Found corresponding differences in exciton optical polarization directions: linear in DQDs, random in QCs and QRs.
- Attributed FSS trends to reduced asymmetry in lateral confinement potential due to compensation effects.
Conclusions:
- Exciton FSS is strongly dependent on the geometric arrangement of QMSs, allowing for effective tuning.
- The geometric arrangement can compensate for strain effects, reducing FSS to levels comparable to strain-free quantum dots.
- This approach offers a pathway to high-symmetry quantum emitters for photon entanglement and spintronic devices using epitaxial growth.
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