Facet evolution of selectively grown epitaxial Si1−xGex fin layers in sub-100 nm trench arrays

•Epitaxial SiGe fin layers were selectively grown in sub-100 nm oxide trench arrays.•Three fin structures were found for the layers with Ge content in the observed range.•The each growth rate of appeared facet surfaces changes the type of fin structures.•Facet evolutions were consistent with the results obtained for three blanket layers.