Reduction of Structural Defects in Ge Epitaxially Grown on Nano-structured Si Islands on SOI Substrate

摘要

One way to further increase performance and/or functionality of Si micro- and nano-electronics is the integration of alternative semiconductors on silicon (Si). We studied the Ge/Si heterosystem with the aim to realize a Ge deposition free of misfit dislocations and with low content of other structural defects. Ge nano-structures were selectively grown by chemical vapor deposition on periodic Si nano-islands (dots and lines) on SOI substrate either directly or with a thin (about 10 nm) SiGe buffer layer. The strain state of the structures was measured by different laboratory-based x-ray diffraction techniques. It was found that a suited SiGe buffer improves the compliance of the Si compared to direct Ge deposition; plastic relaxation during growth can be prevented, and fully elastic relaxation of the structure can be achieved. Transmission electron microscopy confirms that the epitaxial growth of Ge on nano-structured Si is free of misfit dislocations.