Modeling Distributed Kinetics in Isolated Semiconductor Quantum Dots

Published

March 1, 2003

Author(s)

M Kuno, D P. Fromm, S T. Johnson, Alan Gallagher, David Nesbitt

Abstract

tailed modeling of recently observed nonexponential fluorescence intermittency in colloidal semiconductor quantum dots (QDs) is presented. In particular, experiments have shown that both on-time and off-time probability densities generated from single-QD fluorescence trajectories follow an inverse power law, P(τ_on/off)variation}1/τ^1+alpha_{on/off, over multiple decades in time, where the exponent 1+α can, in general, differ for on versus off episodes. Several models are considered and tested against their ability to predict inverse power law behavior in both P(τ}doff^). A physical picture involving electron tunneling to, and return from, traps located several nanometers away from the QD is found to be consistent with the observed P(τ_off), but does not yield the inverse power-law behavior seen in P(au}_on). However, a simple phenomenological model based on exponentially distributed and randomly switched on and off decay rates is analyzed in detail and shown to yield inverse power law behavior in both P(τ_on) and P(τ_off). Monte-Carlo calculations are used to simulate the resulting blinking behavior and are subsequently compared with experimental observations. Most relevantly, these comparisons indicate that the experimental on->off blinking kinetics are independent of excitation intensity, in contradiction with previous multiphoton models of on/off intermittency based on Auger assisted ionization of the QD by recombination of a second electron-hole pair.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Volume

67

Issue

No. 12

Pub Type

Journals

Keywords

fluorescence, semiconductor quantum dots

Citation

Kuno, M. , Fromm, D. , Johnson, S. , Gallagher, A. and Nesbitt, D. (2003), Modeling Distributed Kinetics in Isolated Semiconductor Quantum Dots, Physical Review B (Condensed Matter and Materials Physics) (Accessed July 17, 2024)