Single-exciton optical gain in semiconductor nanocrystals

Victor I Klimov, Sergei A. Ivanov, Jagjit Nanda, Marc Achermann, Ilya Bezel, John A. McGuire, Andrei Piryatinski

Research output: Contribution to journalArticle

726 Citations (Scopus)

Abstract

Nanocrystal quantum dots have favourable light-emitting properties. They show photoluminescence with high quantum yields, and their emission colours depend on the nanocrystal size - owing to the quantum-confinement effect - and are therefore tunable. However, nanocrystals are difficult to use in optical amplification and lasing. Because of an almost exact balance between absorption and stimulated emission in nanoparticles excited with single electron-hole pairs (excitons), optical gain can only occur in nanocrystals that contain at least two excitons. A complication associated with this multiexcitonic nature of light amplification is fast optical-gain decay induced by non-radiative Auger recombination, a process in which one exciton recombines by transferring its energy to another. Here we demonstrate a practical approach for obtaining optical gain in the single-exciton regime that eliminates the problem of Auger decay. Specifically, we develop core/shell hetero-nanocrystals engineered in such a way as to spatially separate electrons and holes between the core and the shell (type-II heterostructures). The resulting imbalance between negative and positive charges produces a strong local electric field, which induces a giant (∼100 meV or greater) transient Stark shift of the absorption spectrum with respect to the luminescence line of singly excited nanocrystals. This effect breaks the exact balance between absorption and stimulated emission, and allows us to demonstrate optical amplification due to single excitons.

Original languageEnglish
Pages (from-to)441-446
Number of pages6
JournalNature
Volume447
Issue number7143
DOIs
Publication statusPublished - May 24 2007

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Quantum Dots
Nanoparticles
Electrons
Light
Luminescence
LDS 751
Genetic Recombination
Color

ASJC Scopus subject areas

  • General

Cite this

Klimov, V. I., Ivanov, S. A., Nanda, J., Achermann, M., Bezel, I., McGuire, J. A., & Piryatinski, A. (2007). Single-exciton optical gain in semiconductor nanocrystals. Nature, 447(7143), 441-446. https://doi.org/10.1038/nature05839

Single-exciton optical gain in semiconductor nanocrystals. / Klimov, Victor I; Ivanov, Sergei A.; Nanda, Jagjit; Achermann, Marc; Bezel, Ilya; McGuire, John A.; Piryatinski, Andrei.

In: Nature, Vol. 447, No. 7143, 24.05.2007, p. 441-446.

Research output: Contribution to journalArticle

Klimov, VI, Ivanov, SA, Nanda, J, Achermann, M, Bezel, I, McGuire, JA & Piryatinski, A 2007, 'Single-exciton optical gain in semiconductor nanocrystals', Nature, vol. 447, no. 7143, pp. 441-446. https://doi.org/10.1038/nature05839
Klimov VI, Ivanov SA, Nanda J, Achermann M, Bezel I, McGuire JA et al. Single-exciton optical gain in semiconductor nanocrystals. Nature. 2007 May 24;447(7143):441-446. https://doi.org/10.1038/nature05839
Klimov, Victor I ; Ivanov, Sergei A. ; Nanda, Jagjit ; Achermann, Marc ; Bezel, Ilya ; McGuire, John A. ; Piryatinski, Andrei. / Single-exciton optical gain in semiconductor nanocrystals. In: Nature. 2007 ; Vol. 447, No. 7143. pp. 441-446.
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