Mapping the spatial distribution of charge carriers in quantum-confined heterostructures

• Type of Material: Article
• Authors: Andrew M. Smith, Emory University; Lucas A. Lane, Emory University; Shuming Nie, Emory University
• Language: English
• Date: 2014-07-31
• Publisher: Nature Publishing Group
• Publication Version: Final Published Version
• Copyright Statement: © 2014, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1038/ncomms5506
• Title of Journal or Parent Work: Nature Communications
• Volume: 5
• Start Page: 4506
• End Page: 4506
• Grant/Funding Information: We wish to thank Dr Hong Yi of Emory University for electron microscopy imaging, Professor Rohit Bhargava and Dr Prabuddha Mukherjee of the University of Illinois at Urbana-Champaign for Raman spectroscopy measurements, and Professor Z.L. Wang of Georgia Tech for high-resolution TEM studies (supported by NSF grant DMR 0922776).; This work was supported by grants from the National Institutes of Health (R01CA163256, RC2CA148265 and HHSN268201000043C to S.N.). A.M.S. acknowledges the NCI Nano-Alliance Program for a Pathway to Independence Award (K99CA154006 and R00CA153914).
• Research Categories: Health Sciences, General; Engineering, Biomedical

Abstract

Quantum-confined nanostructures are considered 'artificial atoms' because the wavefunctions of their charge carriers resemble those of atomic orbitals. For multiple-domain heterostructures, however, carrier wavefunctions are more complex and still not well understood. We have prepared a unique series of cation-exchanged HgxCd1xTe quantum dots (QDs) and seven epitaxial core-shell QDs and measured their first and second exciton peak oscillator strengths as a function of size and chemical composition. A major finding is that carrier locations can be quantitatively mapped and visualized during shell growth or cation exchange simply using absorption transition strengths. These results reveal that a broad range of quantum heterostructures with different internal structures and band alignments exhibit distinct carrier localization patterns that can be used to further improve the performance of optoelectronic devices and enhance the brightness of QD probes for bioimaging. © 2014 Macmillan Publishers Limited. All rights reserved.