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Optical properties of coupled three-dimensional Ge quantum dot crystals
Yingjie Ma1, Zhenyang Zhong, Quan Lv
1State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures Ministry of Education and Department of Physics, Fudan University, Shanghai 200433, China.
Optics Express
|March 14, 2013
Summary
Coupled 3D germanium quantum dot crystals exhibit miniband formation, reducing spectral linewidth and blueshift with increased vertical periodicity. This enhances optical properties for germanium quantum dot crystal applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Optoelectronics
Background:
- Quantum dot crystals (QDCs) offer tunable optical properties.
- Understanding electronic coupling in 3D QDCs is crucial for advanced applications.
Purpose of the Study:
- To investigate the optical properties of coupled 3D germanium quantum dot crystals.
- To elucidate the relationship between vertical periodicity and electronic coupling.
- To analyze the impact of miniband formation on photoluminescence and optical reflectivity.
Main Methods:
- Fabrication of 3D germanium quantum dot crystals with varying vertical periodic numbers.
- Photoluminescence (PL) spectroscopy to analyze spectral linewidth, peak energy blueshift, and phonon replica intensity.
- Optical reflectivity measurements to assess interband absorption.
Main Results:
- Exponential decrease in PL spectral linewidth and excitation power-induced blueshift with increasing vertical periodicity, indicating miniband formation.
- Reduction in transverse-optical (TO) phonon replica intensity with increasing vertical periodicity, attributed to Brillouin-zone folding and relaxed indirect transition nature.
- Significantly reduced optical reflectivity in 3D QDCs compared to disordered QDs, signifying enhanced interband absorption due to miniband formation.
Conclusions:
- Vertical electronic coupling in 3D Ge QDCs leads to miniband formation.
- Miniband formation significantly influences photoluminescence and optical absorption characteristics.
- These findings highlight the potential of 3D Ge QDCs for optoelectronic devices.
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