A finned structure is fabricated using a bulk silicon substrate having a carbon doped epitaxial silicon layer. A pFET region of the structure includes silicon germanium fins. Such fins are formed by annealing the structure to mix a germanium containing layer with an adjoining crystalline silicon layer. The structure further includes an nFET region including silicon fins formed from the crystalline silicon layer. The germanium containing layer in the nFET region is removed to create a space beneath the crystalline silicon layer in the nFET region. An insulating material is provided within the space. The pFET and nFET regions are electrically isolated by a shallow trench isolation region.