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Excitons and biexcitons in InGaN quantum dot like localization centers
S Amloy1, K F Karlsson, M O Eriksson
1Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden. Department of Physics, Faculty of Science, Thaksin University, Phattalung 93110, Thailand. supaluck.a@tsu.ac.th
Nanotechnology
|November 21, 2014
Summary
Indium segregation in InGaN quantum wells forms quantum dot-like centers. These centers exhibit varying biexciton binding energies, confirming their three-dimensional quantum confinement and quantum dot properties.
Area of Science:
- Semiconductor physics
- Materials science
- Quantum optics
Background:
- Indium segregation in Indium Gallium Nitride (InGaN) quantum wells is crucial for optoelectronic device performance.
- Understanding exciton localization centers is key to controlling light emission properties.
Purpose of the Study:
- To investigate the nature of quantum dot (QD)-like exciton localization centers formed by indium segregation in InGaN single quantum wells.
- To correlate the geometric properties of these centers with their optical characteristics, specifically exciton and biexciton binding energies.
Main Methods:
- Cross-section transmission electron microscopy (TEM) to determine QD-like feature size and shape.
- Scanning near-field optical microscopy (SNOM) to map the spatial distribution of optically active centers.
- Microphotoluminescence (μ-PL) spectroscopy with excitation power dependencies to identify single-center emissions and measure binding energies.
Main Results:
- TEM revealed QD-like features with lateral sizes of 1-5 nm.
- SNOM and μ-PL showed inhomogeneous spatial and spectral distributions of localization centers.
- Biexciton binding energy (E(b)xx) varied from 3 to -22 meV, correlating with exciton emission energy.
- Negative binding energies confirmed 3D quantum confinement, indicative of QD-like behavior.
Conclusions:
- Indium segregation effectively creates QD-like localization centers in InGaN quantum wells.
- The observed correlation between E(b)xx and exciton energy suggests variations in lateral confinement size.
- Recombination lifetimes further support the 3D confinement model for these QD-like structures.
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