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- Title
Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor.
- Authors
Bo Zhang; Yong Xiang; Shrestha, Santosh; Green, Martin; Conibeer, Gavin
- Abstract
Ge nanocrystals (Ge-ncs) embedded in a SiO2 superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge- O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen-deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx) was then proposed to explain these findings and supplement the existing growth models for Ge-ncs in SiO2 films. Further analysis of the bonding structure of Ge atoms suggested that Ge-ncs are likely to have a core-shell structure with an amorphous-like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.
- Subjects
GERMANIUM crystals; CRYSTAL growth; SURFACE structure; NANOCRYSTALS; CHEMICAL sample preparation; GERMANIUM compounds; TERNARY alloys; CHEMICAL precursors
- Publication
Journal of Nanomaterials, 2014, p1
- ISSN
1687-4110
- Publication type
Article
- DOI
10.1155/2014/161637