We have developed a method using local oxidation on silicon to create nanoscale silicon seeds for the lateral epitaxial overgrowth of germanium on silicon oxide. The germanium growth starts selectively from silicon seed lines, proceeds by wetting the SiO2 layer and coalesces without formation of grain boundary. Analysis by high resolution transmission electron microscopy have shown that Ge layers grown above silicon oxide are perfectly monocrystalline and are free of defect. The only detected defects are situated at the Ge∕Si interface. Geometrical phase analyses of the microscopy images have shown that the Ge layer is fully relaxed and homogeneous.

In this paper, we present our studies on the growth kinetics of Ge crystals on silicon oxide by nanoscale seed induced lateral epitaxy. We propose a simple and reliable method based on standard local oxidation of silicon technique for creating nanoscale silicon seeds at the edge of thermally grown silicon oxide stripes of desired thickness. The growth of Ge from germane is initiated in the two silicon seed lines and evolves toward a complete wetting of the SiO 2 stripe after coalescence. The wetting mechanism of SiO 2 by Ge is strongly dependent on the seed orientation and closely related to the development of ͕111͖ facets. The coalescence of adjacent Ge crystals results in an improvement in the organization of the initial material. As a result, no defect is visible in the inner part of the structure. The observed defects are arrays of misfit dislocations standing along the seed lines, while only few dislocations are visible through the Ge crystal. Geometric phase analysis of high resolution transmission electron microscopy images and x-ray diffraction reciprocal space maps show that the so-grown Ge crystal stripes on SiO 2 layer are fully relaxed, homogeneous, and fully coherent along their length. The main deviation regarding a perfect epitaxial relation with the silicon substrate is a tilt of Ϯ0.6°around the longitudinal axis of stripe crystals.

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