Germanium-silicon core-shell nanowire (NW) heterostructures are promising building blocks to enable improved performance of nanophotonic and nanoelectronic devices. However, surface passivation is an important requirement for realization of NW-based devices: Small diameter Ge nanowires have large surface area-to-volume ratio, and carrier scattering and recombination at the surface defects may significantly compromise the electronic and optoelectronic properties of nanowire devices. One promising approach to passivating Ge NWs is to deposit an epitaxial shell of Si or SiGe around them. This paper describes the details of chemical vapor deposition growth of single crystal Ge core-Si(Ge) shell nanowires that are not intentionally doped and have coherent core-shell interfaces. Methods for quantitative local composition and strain measurements of these coaxial heterostructures are highlighted.
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