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

Fingerprint

population inversion
Semiconductor quantum dots
quantum dots
Excitons
depletion
excitons
traps
Optical gain
Stimulated emission
Emission spectroscopy
stimulated emission
Excited states
excitation
rods
life (durability)
Atoms
electronics
spectroscopy
atoms
interactions

Keywords

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

ASJC Scopus subject areas

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

Cite this

Long-lived population inversion in isovalently doped quantum dots. / Lahad, Ohr; Meir, Noga; Pinkas, Iddo; Oron, Dan.

In: ACS Nano, Vol. 9, No. 1, 27.01.2015, p. 817-824.

Research output: Contribution to journalArticle

Lahad, Ohr ; Meir, Noga ; Pinkas, Iddo ; Oron, Dan. / Long-lived population inversion in isovalently doped quantum dots. In: ACS Nano. 2015 ; Vol. 9, No. 1. pp. 817-824.
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