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We report on structural properties and charge trapping in [(Ge+SiO2)/SiO2]×2 films deposited by magnetron sputtering on a periodically corrugated-rippled substrate and annealed in vacuum and forming gas. The rippled substrate caused a self-ordered growth of Ge quantum dots, while annealing in different environments enabled us to separate charge trapping in quantum dots from the trapping at the dot-matrix and matrix-substrate interfaces. We show that the charge trapping occurs mainly in Ge quantum dots in the films annealed in the forming gas, while Si-SiO2 interface trapping is dominant for the vacuum annealed films. [ABSTRACT FROM AUTHOR]

We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Germanium Quantum Dots (Ge QDs) were formed in SiO2 by RT magnetron sputtering co-deposition of Ge and SiO2 and subsequent annealing. Films were deposited in the form of alternating (Ge+SiO2) layers (40:60 molar ratio) and pure SiO2 layers, serving as spacers. Grazing incidence small angle x-ray scattering (GISAXS) was applied for structural characterization of the QDs synthesized in the SiO2 amorphous matrix. The chemical composition and phase of the QDs were determined by Raman spectroscopy, and the spatial distribution and concentration of the Ge atoms by Rutherford Backscattering. The 2D GISAXS patterns, besides giving information on the layered structure, were used to reveal the onset of the synthesis of Ge QDs in SiO2 and to determine the average size and shape of QDs. It has been shown that the insertion of spacer SiO2 layers between (Ge+SiO2) layers transforms the 3D growth of Ge QDs into a preferentially 2D growth, within each 7 nm thick (Ge+SiO2) layer. This resulted in a considerably smaller average size of Ge QDs in the layered films. The synthesis of well crystallized, moderately sized, spherical Ge QDs was achieved by post-deposition annealing in the 700–800 ∘C range. [Copyright &y& Elsevier]