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Ultrafast charge-carrier dynamics of copper oxide nanocrystals Holzman, Jonathan F.; Born, Brandon; Geoffroy-Gagnon, Simon; Collier, Christopher Michael; Krupa, Jeffrey D. A.; Hristovski, Ilija R.

Abstract

In this work, a detailed investigation is carried out on copper oxide, in the form of cupric oxide (CuO) nanocrystals. Particular attention is paid to the bandstructure and ultrafast charge-carrier dynamics. Transient absorption spectroscopy is carried out with an above-bandgap pump beam and below-bandgap probe beam to glean insight on the relaxation and recombination dynamics of the CuO nanocrystals at various pump fluences. Three time constants are apparent. The first time constant varies with pump fluence from 330 fs to 630 fs, and it is attributed to momentum relaxation via carrier-carrier scattering in the valence band as well as exciton-exciton annihilation. The second time constant is constant at 2 ps, and it is attributed to energy relaxation via carrier-phonon scattering within the valence band. The third time constant is constant at 50 ps, and it is attributed to trapping and recombination, due to the high density of trap states within the CuO nanocrystals. Such findings lay the foundation for future studies and applications of the emerging CuO material system.

Item Metadata

Title
Ultrafast charge-carrier dynamics of copper oxide nanocrystals
Creator
Holzman, Jonathan F.; Born, Brandon; Geoffroy-Gagnon, Simon; Collier, Christopher Michael; Krupa, Jeffrey D. A.; Hristovski, Ilija R.
Publisher
American Chemical Society
Description
In this work, a detailed investigation is carried out on copper oxide, in the form of cupric oxide (CuO) nanocrystals. Particular attention is paid to the bandstructure and ultrafast charge-carrier dynamics. Transient absorption spectroscopy is carried out with an above-bandgap pump beam and below-bandgap probe beam to glean insight on the relaxation and recombination dynamics of the CuO nanocrystals at various pump fluences. Three time constants are apparent. The first time constant varies with pump fluence from 330 fs to 630 fs, and it is attributed to momentum relaxation via carrier-carrier scattering in the valence band as well as exciton-exciton annihilation. The second time constant is constant at 2 ps, and it is attributed to energy relaxation via carrier-phonon scattering within the valence band. The third time constant is constant at 50 ps, and it is attributed to trapping and recombination, due to the high density of trap states within the CuO nanocrystals. Such findings lay the foundation for future studies and applications of the emerging CuO material system.
Subject
ultrafast charge-carrier dynamics; transient absorption pump-probe spectroscopy; emtosecond carrier-carrier scattering; trap-assisted reco mbination; mid-gap state; exciton-exciton annihilation; semiconductor nanocrystals
Genre
Article
Type
Text
Language
eng
Date Available
2018-03-19
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0364286
URI
http://hdl.handle.net/2429/64850
Affiliation
Applied Science, Faculty of; Non UBC; Engineering, School of (Okanagan)
Citation
B. Born, J. D. A. Krupa, S. Geoffroy-Gagnon, I. R. Hristovski, C. M. Collier, and J. F. Holzman, "Ultrafast charge-carrier dynamics of copper oxide nanocrystals," ACS Photonics, vol. 3, pp. 2475-2481, 2016.
Publisher DOI
10.1021/acsphotonics.6b00717
Peer Review Status
Reviewed
Scholarly Level
Faculty
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
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DSpace

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Attribution-NonCommercial-NoDerivatives 4.0 International