Semiconductor-on-insulator (SOI) structures, semiconductor devices using the same and methods of manufacturing the same, and more particularly, to a structure with a single-crystalline (for example, germanium (x-Ge)) layer on an insulating layer, semiconductor devices using the same, and methods of manufacturing the same. The SOI structure may include a single-crystalline substrate formed of a first semiconductor material, a first insulating layer formed on the substrate and having at least one window exposing a portion of the substrate, a first epitaxial growth region formed on a surface of the substrate exposed by the window and formed of at least one of the first semiconductor material and a second semiconductor material, and a first single-crystalline layer formed on the first insulating layer and the first epitaxial growth region and formed of the second semiconductor material, and crystallized using a surface of the first epitaxial growth region as a seed layer for crystallization.