Molecular beam epitaxial growth of CoSi₂ on porous Si

CoSi₂ epitaxial layers with different thicknesses have been grown onto porous-Si substrates by molecular beam epitaxy. Good crystallinity is obtained for CoSi₂ films thicker than 50 nm. The use of a thin buffer layer is found to be crucial in order to achieve abrupt interface and good crystallinity. Planar view transmission electron microscope images obtained from 30-nm-thick CoSi₂ buffer-Si/porous-Si samples indicate that a large area of the epitaxial film is dislocation free, in contrast with a uniform distribution of misfit dislocations across relaxed CoSi₂/single- crystal Si samples of the same thickness. This study suggests a possible pseudomorphic growth by using porous Si as a substrate.