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Photoluminescence ring formation in coupled quantum wells: excitonic versus ambipolar diffusion
1Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot, Israel. mstern@weizmann.ac.il
Physical Review Letters
|December 31, 2008
Summary
We investigated photoexcited carrier diffusion in quantum wells near the Mott transition. Ambipolar diffusion was observed, but excitonic correlations significantly suppressed it, creating a unique photoluminescence ring pattern.
Area of Science:
- Condensed matter physics
- Quantum optics
- Semiconductor physics
Background:
- The Mott transition signifies a phase change in materials where strong electron-electron interactions localize electrons, leading to insulating behavior.
- Understanding carrier dynamics is crucial for developing novel electronic and optoelectronic devices.
Purpose of the Study:
- To investigate the diffusion properties of photoexcited carriers in coupled quantum wells.
- To analyze the influence of the Mott transition and excitonic correlations on carrier diffusion.
- To explore the relationship between diffusion characteristics and observed photoluminescence patterns.
Main Methods:
- Studying the diffusion of photoexcited carriers in coupled quantum wells.
- Analyzing carrier behavior around the Mott transition.
- Observing photoluminescence patterns.
Main Results:
- Photoexcited carrier diffusion is ambipolar with a large diffusion coefficient, comparable to p-i-n junctions.
- Excitonic correlations in the excitonic phase markedly reduce carrier diffusion.
- A distinct photoluminescence ring pattern emerges around the excitation spot at the Mott transition due to differing diffusion properties.
Conclusions:
- Carrier diffusion in coupled quantum wells is significantly affected by the Mott transition and electron-electron interactions.
- The observed photoluminescence ring is a direct consequence of suppressed carrier diffusion caused by excitonic correlations.
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