Long-Lived Population Inversion in Isovalently Doped Quantum Dots
| Autor: | Iddo Pinkas, Ohr Lahad, Noga Meir, Dan Oron |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Auger effect
Chemistry Doping General Engineering General Physics and Astronomy Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Population inversion symbols.namesake Quantum dot Excited state symbols General Materials Science Spontaneous emission Stimulated emission Atomic physics Spectroscopy |
| Zdroj: | ACS Nano. 9:817-824 |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/nn506404n |
| Popis: | Optical gain from colloidal quantum dots has been desired for several decades since their discovery. While gain from multiexcitations is by now well-established, nonradiative Auger recombination limits the lifetime of such population inversion in quantum dots. CdSe cores isovalently doped by one to few Te atoms capped with rod-shaped CdS are examined as a candidate system for enhanced stimulated emission properties. Emission depletion spectroscopy shows a behavior characteristic of 3-level gain systems in these quantum dots. This implies complete removal of the 2-fold degeneracy of the lowest energy electronic excitation due to the large repulsive exciton-exciton interaction in the doubly excited state. Using emission depletion measurements of the trap-associated emission from poorly passivated CdS quantum dots, we show that 3-level characteristics are typical of emission resulting from a band edge to trap state transition, but reveal subtle differences between the two systems. These results allow for unprecedented observation of long-lived population inversion from singly excited quantum dots. |
| Databáze: | OpenAIRE |
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