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Dynamics of Trion formation in InxGa1-xAs quantum wells
M T Portella-Oberli1, J Berney, L Kappei
1Institut de Photonique et Electronique Quantiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH1015 Lausanne, Switzerland.
Physical Review Letters
|April 28, 2009
Summary
Charged excitons (trions) form via bi- and trimolecular pathways, leading to coexisting positive and negative trions in quantum wells. This model explains exciton decay times in doped semiconductors.
Area of Science:
- Solid State Physics
- Quantum Mechanics
- Semiconductor Nanostructures
Background:
- Charged excitons, or trions, are fundamental quasiparticles in semiconductor quantum wells.
- Understanding trion formation mechanisms is crucial for optoelectronic device applications.
- Previous models struggled to reconcile theoretical and experimental exciton decay times in doped quantum wells.
Purpose of the Study:
- To elucidate the formation mechanism of charged excitons (trions) in quantum wells.
- To demonstrate the coexistence of both positive and negative trions.
- To resolve discrepancies in exciton radiative decay time measurements.
Main Methods:
- Development of a double pathway model for trion formation.
- Time-resolved photoluminescence spectroscopy on high-quality InxGa1-xAs quantum wells.
- Analysis of photoluminescence contributions from excitons, trions, and band-edge emission.
Main Results:
- Established a double pathway mechanism involving bi- and trimolecular processes for trion formation.
- Confirmed the simultaneous existence of negatively and positively charged excitons, irrespective of excess carrier concentration.
- Successfully explained the long-standing discrepancy between theoretical and experimental exciton radiative decay times in doped quantum wells.
Conclusions:
- The proposed double pathway model provides a comprehensive understanding of trion dynamics in quantum wells.
- The findings offer new insights into carrier interactions and recombination processes in semiconductor nanostructures.
- This work paves the way for improved design and performance of quantum well-based devices.
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