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Title: Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions

Abstract

To evaluate the role of nonphonon energy relaxation mechanisms in quantum dots and in particular the role of electron-hole (e-h) interactions, we have studied femtosecond carrier dynamics in CdSe colloidal nanoparticles in which the e-h separation (coupling) is controlled using different types of surface ligands. In dots capped with hole accepting molecules, the e-h coupling is strongly reduced after the hole is transferred to a capping group. By re-exciting an electron within the conduction band at different stages of hole transfer and monitoring its relaxation back into the ground state, we observe a more than tenfold increase in the electron relaxation time (from 250 fs to 3 ps) after the completion of the hole transfer to the capping molecule. This strongly indicates that electron relaxation in quantum dots is dominated not by phonon emission but by the e-h energy transfer. (c) 2000 The American Physical Society.

Authors:
 [1];  [1];  [1];  [2];  [2]
  1. Chemical Science and Technology Division, CST-6, MS-J585, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  2. Department of Chemistry and Center for Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
20216568
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 61; Journal Issue: 20; Other Information: PBD: 15 May 2000; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ELECTRON-HOLE COUPLING; SEMICONDUCTOR JUNCTIONS; ELECTRONIC STRUCTURE; RELAXATION; PHONONS; CHARGE CARRIERS; EXPERIMENTAL DATA

Citation Formats

Klimov, V. I., Mikhailovsky, A. A., McBranch, D. W., Leatherdale, C. A., and Bawendi, M. G. Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions. United States: N. p., 2000. Web. doi:10.1103/PhysRevB.61.R13349.
Klimov, V. I., Mikhailovsky, A. A., McBranch, D. W., Leatherdale, C. A., & Bawendi, M. G. Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions. United States. doi:10.1103/PhysRevB.61.R13349.
Klimov, V. I., Mikhailovsky, A. A., McBranch, D. W., Leatherdale, C. A., and Bawendi, M. G. Mon . "Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions". United States. doi:10.1103/PhysRevB.61.R13349.
@article{osti_20216568,
title = {Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions},
author = {Klimov, V. I. and Mikhailovsky, A. A. and McBranch, D. W. and Leatherdale, C. A. and Bawendi, M. G.},
abstractNote = {To evaluate the role of nonphonon energy relaxation mechanisms in quantum dots and in particular the role of electron-hole (e-h) interactions, we have studied femtosecond carrier dynamics in CdSe colloidal nanoparticles in which the e-h separation (coupling) is controlled using different types of surface ligands. In dots capped with hole accepting molecules, the e-h coupling is strongly reduced after the hole is transferred to a capping group. By re-exciting an electron within the conduction band at different stages of hole transfer and monitoring its relaxation back into the ground state, we observe a more than tenfold increase in the electron relaxation time (from 250 fs to 3 ps) after the completion of the hole transfer to the capping molecule. This strongly indicates that electron relaxation in quantum dots is dominated not by phonon emission but by the e-h energy transfer. (c) 2000 The American Physical Society.},
doi = {10.1103/PhysRevB.61.R13349},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 20,
volume = 61,
place = {United States},
year = {2000},
month = {5}
}