Long-lived population inversion in isovalently doped quantum dots

Ohr Lahad, Noga Meir, Iddo Pinkas, Dan Oron

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)817-824
Number of pages8
JournalACS nano
Volume9
Issue number1
DOIs
Publication statusPublished - Jan 27 2015

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Keywords

  • isovalent doping
  • optical gain
  • quantum dots
  • stimulated emission
  • trap emission

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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