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Califano, M (2009) Direct and inverse auger processes in InAs nanocrystals: can the decay signature of a trion be mistaken for carrier multiplication? ACS Nano, 3 (9). 2706 - 2714. ISSN 1936-0851
Abstract
A complete and detailed theoretical investigation of the main processes involved in the controversial detection and quantification of carrier multiplication (CM) is presented, providing a coherent and comprehensive picture of excited state relaxation in InAs nanocrystals (NCs). The observed rise and decay times of the 1S transient bleach are reproduced, in the framework of the Auger model, using an atomistic semiempirical pseudopotential method, achieving excellent agreement with experiment. The CM time constants for small core-only and core/shell nanocrystals are obtained as a function of the excitation energy, assuming an impact-ionization-like process. The resulting lifetimes at energies close to the observed CM onset are consistent with the upper limits deduced experimentally from PbSe and CdSe samples. Most interestingly, as the Auger recombination lifetimes calculated for charged excitons are found to be of a similar order of magnitude to those computed for biexcitons, both species are expected to exhibit the fast decay component in NC population dynamics so far attributed exclusively to the presence of biexcitons and therefore identified as the signature of CM occurrence in high-energy low-pump-fluence spectroscopic studies. However, the ratio between trions and biexcitons time constants is found to be larger than the typical experimental accuracy. It is therefore concluded that, in InAs NCs, it should be experimentally possible to discriminate between the two species and that the origin of the observed discrepancies in CM yields is unlikely to lay in the presence of charged excitons.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Keywords: | Carrier multiplication; InAs nanocrystals; Auger processes; pseudopotential method; excited state relaxation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Pollard Institute (Leeds) |
Depositing User: | Repository Officer |
Date Deposited: | 26 Mar 2015 10:46 |
Last Modified: | 29 Mar 2018 05:12 |
Published Version: | http://dx.doi.org/10.1021/nn900461f |
Status: | Published |
Publisher: | American Chemical Society |
Refereed: | Yes |
Identification Number: | 10.1021/nn900461f |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:75636 |
Available Versions of this Item
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Direct and inverse Auger processes in InAs nanocrystals: can the decay signature of a trion be mistaken for carrier multiplication? (deposited 09 Dec 2009 16:03)
- Direct and inverse auger processes in InAs nanocrystals: can the decay signature of a trion be mistaken for carrier multiplication? (deposited 26 Mar 2015 10:46) [Currently Displayed]