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Dense Ge nanocrystal layers embedded in oxide obtained by controlling the diffusion–crystallization process

  • Ana-Maria Lepadatu
  • Toma Stoica
  • Ionel Stavarache
  • Valentin Serban Teodorescu
  • Dan Buca
  • Magdalena Lidia Ciurea
Research Paper

Abstract

Amorphous Ge/SiO2 multilayer structures deposited by magnetron sputtering have been annealed at different temperatures between 650 and 800 °C for obtaining Ge nanocrystals in oxide matrix. The properties of the annealed structures were investigated by transmission electron microscopy, Raman spectroscopy, and low temperature photoluminescence. The Ge crystallization is partially achieved at 650 °C and increases with annealing temperature. Insight of the Ge nanocrystal formation was acquired by comparing two annealing procedures, i.e., in a conventional tube furnace and by a rapid thermal annealing. By rapid thermal annealing in comparison to conventional furnace one, the Ge crystallization process is faster than Ge diffusion, resulting in the formation of more compact layers of Ge nanocrystals with 8–9.5-nm size as Raman spectroscopy reveals. These findings are important to improve the annealing efficiency in the nanocrystals formation for a precise control of their sizes and location in oxide matrix and for the possibility to create systems with interacting nanoparticles for charge or excitonic transfer. The infrared photoluminescence of Ge nanocrystals at low temperatures shows strong emission with two sharp peaks at about 1,000 meV.

Keywords

Ge/SiO2 multilayer structures Ge diffusion Ge nanocrystal formation TEM Raman spectroscopy Photoluminescence 

Notes

Acknowledgments

This study was performed partially under the auspices of the National Research Council—Executive Agency for Higher Education, Research, Development and Innovation Funding (CNCS—UEFISCDI), by funding projects No. PN II-PT-PCCA-9/2012 and No. PN II-RU-PD-2011/3/0094.

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Ana-Maria Lepadatu
    • 1
    • 2
    • 3
  • Toma Stoica
    • 3
  • Ionel Stavarache
    • 1
  • Valentin Serban Teodorescu
    • 1
  • Dan Buca
    • 3
  • Magdalena Lidia Ciurea
    • 1
    • 4
  1. 1.National Institute of Materials PhysicsMagureleRomania
  2. 2.Faculty of PhysicsUniversity of BucharestMagureleRomania
  3. 3.Peter Grünberg Institute (PGI-9), Forschungszentrum JülichJülichGermany
  4. 4.Academy of Romanian ScientistsBucurestiRomania

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