Intermixing During SiGe Heteroeptixy

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Technical: This project seeks comprehensive understanding of intermixing during heteroepitaxy, with Ge/Si(100) as a model system. The approach is to manipulate growth kinetics to assist in identifying and isolating specific processes to assess their contributions to intermixing. This includes the application of 'surfactant' effects to modify surface segregation and surface diffusion kinetics. The effects of inhomogeneous elastic fields induced by 3D island growth on bulk and surface diffusion will be addressed specifically. A combination of sub-nm spatial resolution, quantitative electron microscopy and selective chemical etching will be employed to form composition maps with nm spatial resolution in 3 dimensions. Electron microscope techniques will provide average composition variations along the primary beam direction to form a 2D projection of 3D composition profiles. Selective etching techniques will be employed, in combination with atomic force microscopy, to form isocomposition topographs. Combining these methods is expected to enable new insight into composition modulation in islanded epitaxial heterostructures. The capability of these selective etching methods will be extended by exploiting the water solubility of Ge oxides and by employing etch chemistries selective for Si over SiGe in order to quantitatively investigate the composition of buried Ge islands. Non-technical: The project addresses basic research issues in a topical area of electronic/photonic materials science with high technological relevance. Research and educational activities will be integrated with involvement of both graduate and undergraduates in the research program. The investigators will also link closely with the education and outreach infrastructure of the ASU Center for Solid State Science, which encompasses an Industrial Associates Program.