Synthesis and characterization of germanium/Si-alkyl and germanium/silica core-shell quantum dots

Chung Sung Yang, Susan M. Kauzlarich, Y. C. Wang

Research output: Contribution to journalArticle

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Abstract

Ge/Si-R and Ge/SiO2 core-shell nanoparticles have been synthesized by a solution route from the stepwise reactions of the Zintl salt, Mg2Ge, with SiCl4 and subsequently either RLi (R = butyl) or H2O2. High-resolution transmission electron microscopy (HRTEM) images show that the core part of these Ge/Si-R and Ge/SiO2 nanoparticles is crystalline and the d spacing of lattice fringes agrees with the {111} crystal plane (3.27 Å) of Ge. The average sizes (diameter) are 5.8(2.3) and 6.8(2.8) nm for Ge/Si-R and Ge/SiO2, respectively. Fourier transform-infrared (FTIR) spectra are consistent with alkyl groups bonded to the silicon surface in Ge/Si-R nanoclusters. Off-axis holography was performed for several Ge/SiO2 nanoparticles. The characterization of the ratio of radii and geometry between the core part and the outer sphere of Ge/SiO2 is presented. The reconstructed phase image from the hologram offers detailed information concerning the ratio of the shell thickness (R - r) to the radius of the core (r), Rr = (R - r)/r, by measuring the phase shift and the resultant phase contrast. The Rr value from the deconvoluted phase image of a 16 nm spherelike Ge/SiO2 is 0.264 (0.065). Photoluminescence (PL) spectra of both Ge/Si-R and Ge/SiO2 nanoclusters show a strong UV-blue PL with a peak centered between 400 and 410 nm. These results suggest that the UV-blue PL may be attributed to the core part of these nanoparticles.

Original languageEnglish (US)
Pages (from-to)3666-3670
Number of pages5
JournalChemistry of Materials
Volume11
Issue number12
StatePublished - 1999

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Germanium
Silicon Dioxide
Semiconductor quantum dots
Silica
Nanoparticles
Photoluminescence
Nanoclusters
Holography
Holograms
Silicon
High resolution transmission electron microscopy
Phase shift
Crystal lattices
Fourier transforms
Salts
Crystalline materials
Infrared radiation
Crystals
Geometry

ASJC Scopus subject areas

  • Materials Chemistry
  • Materials Science(all)

Cite this

Synthesis and characterization of germanium/Si-alkyl and germanium/silica core-shell quantum dots. / Yang, Chung Sung; Kauzlarich, Susan M.; Wang, Y. C.

In: Chemistry of Materials, Vol. 11, No. 12, 1999, p. 3666-3670.

Research output: Contribution to journalArticle

Yang, Chung Sung ; Kauzlarich, Susan M. ; Wang, Y. C. / Synthesis and characterization of germanium/Si-alkyl and germanium/silica core-shell quantum dots. In: Chemistry of Materials. 1999 ; Vol. 11, No. 12. pp. 3666-3670.
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