Near-infrared photoluminescence enhancement in Ge/CdS and Ge/ZnS core/shell nanocrystals: Utilizing IV/II-VI semiconductor epitaxy

dc.contributor.author Guo, Yijun
dc.contributor.author Rowland, Clare
dc.contributor.author Schaller, Richard
dc.contributor.author Vela, Javier
dc.contributor.department Ames National Laboratory
dc.contributor.department Chemistry
dc.date 2018-02-17T06:37:57.000
dc.date.accessioned 2020-06-30T01:17:47Z
dc.date.available 2020-06-30T01:17:47Z
dc.date.copyright Wed Jan 01 00:00:00 UTC 2014
dc.date.embargo 2015-07-10
dc.date.issued 2014-07-10
dc.description.abstract <p>Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or doping. Colloidal Ge nanocrystals are particularly interesting in the development of near-infrared materials for applications in bioimaging, telecommunications and energy conversion. Epitaxial growth of a passivating shell is a common strategy employed in the synthesis of highly luminescent II-VI, III-V and IV-VI semiconductor quantum dots. Here, we use relatively unexplored IV/II-VI epitaxy as a way to enhance the photoluminescence and improve the optical stability of colloidal Ge nanocrystals. Selected on the basis of their relatively small lattice mismatch compared with crystalline Ge, we explore the growth of epitaxial CdS and ZnS shells using the successive ion layer adsorption and reaction method. Powder X-ray diffraction and electron microscopy techniques, including energy dispersive X-ray spectroscopy and selected area electron diffraction, clearly show the controllable growth of as many as 20 epitaxial monolayers of CdS atop Ge cores. In contrast, Ge etching and/or replacement by ZnS result in relatively small Ge/ZnS nanocrystals. The presence of an epitaxial II-VI shell greatly enhances the near-infrared photoluminescence and improves the photoluminescence stability of Ge. Ge/II-VI nanocrystals are reproducibly 1-3 orders of magnitude brighter than the brightest Ge cores. Ge/4.9CdS core/shells show the highest photoluminescence quantum yield and longest radiative recombination lifetime. Thiol ligand exchange easily results in near-infrared active, water-soluble Ge/II-VI nanocrystals. We expect this synthetic IV/II-VI epitaxial approach will lead to further studies into the optoelectronic behavior and practical applications of Si and Ge-based nanomaterials.</p>
dc.description.comments <p>Reprinted (adapted) with permission from <em>ACS Nano</em> 8 (2014): 8334, doi:<a href="http://dx.doi.org/10.1021/nn502792m" target="_blank">10.1021/nn502792m </a>. Copyright 2014 American Chemical Society.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/chem_pubs/129/
dc.identifier.articleid 1116
dc.identifier.contextkey 7876633
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath chem_pubs/129
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/14561
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/chem_pubs/129/0-2014_VelaJ_NearInfraredPhotoluminescence.pdf|||Fri Jan 14 19:32:45 UTC 2022
dc.source.bitstream archive/lib.dr.iastate.edu/chem_pubs/129/2014_VelaJ_NearInfraredPhotoluminescence.pdf|||Fri Jan 14 19:32:46 UTC 2022
dc.source.uri 10.1021/nn502792m
dc.subject.disciplines Chemistry
dc.subject.keywords core/shell nanocrystals
dc.subject.keywords germanium
dc.subject.keywords IV/II-VI epitaxy
dc.subject.keywords near-IR photoluminescence
dc.subject.keywords quantum dots
dc.title Near-infrared photoluminescence enhancement in Ge/CdS and Ge/ZnS core/shell nanocrystals: Utilizing IV/II-VI semiconductor epitaxy
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication b1daee7a-1960-41bd-a41e-6d4625912766
relation.isOrgUnitOfPublication 25913818-6714-4be5-89a6-f70c8facdf7e
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
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