Alloy formation at the tetrapod core/arm interface

Weiwei Zheng, Zhenxing Wang, Johan Van Tol, Naresh S. Dalal, Geoffrey F. Strouse

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

The nature of the interfacial structure between the core and the arms of a tetrapod quantum dot (QD) formed during the heteroepitaxial growth of a ZnS arm onto a CdSe core is not well understood but can be analyzed through the use of high-frequency electron paramagnetic resonance (HF-EPR) spectroscopy. The spectroscopic resolution at high frequency allows the presence of unique crystal fields reflecting interfacial alloying to be analyzed by incorporating Mn(II) ions as a dopant into the QD to act as an intentional EPR active spectroscopic probe. In addition, the HF-EPR can spectroscopically observe the presence of ion vacancies that are anticipated to form at the heteroepitaxial interface to accommodate structural mismatch. The HF-EPR spectra for Mn(II) are extremely sensitive to perturbations of the microenvironment due to changes in the crystal field. The HF-EPR spectra of Mn(II) in a CdSe (core)/ZnS (arm) tetrapod exhibiting wurtzite symmetry for both core and interface of the tetrapod provide clear evidence of heteroalloying at the core-arm interface and formation of intrinsic dislocations at grain boundaries. The formation of the interfacial alloy and grain boundaries reflects short-range ion migration at the heteroepitaxial layer to reduce strain energy due to the 12% lattice mismatch between the wurtzite lattices of CdSe and ZnS.

Original languageEnglish (US)
Pages (from-to)3132-3137
Number of pages6
JournalNano Letters
Volume12
Issue number6
DOIs
StatePublished - Jun 13 2012

Keywords

  • Core/shell quantum dots
  • alloy formation
  • diluted magnetic semiconductor quantum dots
  • high-frequency EPR
  • lattice mismatch
  • strain

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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