Publication
Title
Nature of the positron state in CdSe quantum dots
Author
Abstract
Previous studies have shown that positron-annihilation spectroscopy is a highly sensitive probe of the electronic structure and surface composition of ligand-capped semiconductor quantum dots (QDs) embedded in thin films. The nature of the associated positron state, however, whether the positron is confined inside the QDs or localized at their surfaces, has so far remained unresolved. Our positron-annihilation lifetime spectroscopy studies of CdSe QDs reveal the presence of a strong lifetime component in the narrow range of 358371 ps, indicating abundant trapping and annihilation of positrons at the surfaces of the QDs. Furthermore, our ab initio calculations of the positron wave function and lifetime employing a recent formulation of the weighted density approximation demonstrate the presence of a positron surface state and predict positron lifetimes close to experimental values. Our study thus resolves the long-standing question regarding the nature of the positron state in semiconductor QDs and opens the way to extract quantitative information on surface composition and ligand-surface interactions of colloidal semiconductor QDs through highly sensitive positron-annihilation techniques.
Language
English
Source (journal)
Physical review letters. - New York, N.Y.
Physical review letters. - New York, N.Y.
Publication
New York, N.Y. : 2018
ISSN
0031-9007
Volume/pages
121 :5 (2018) , 6 p.
Article Reference
057401
ISI
000440635300012
Pubmed ID
30118267
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Project info
First-principles positron spectroscopy of topological insulators.
NMI3: Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy
SOLARPAINT: Understanding the durability of light sensitive materials: transferring insights between solar cell physics and the chemistry of paintings.
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 04.09.2018
Last edited 07.11.2021
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