Growth of Si/SiGe superlattices on Si substrates by molecular beam epitaxy (MBE) is described. Strain symmetrization in the superlattice is achieved with an incommensurate SiGe buffer layer. The concept of strainsymmetrization is explained and properties of buffer and strained layer superlattices are investigated. A twodimensional electron gas with enhanced room temperature mobility and folded phonon modes within the reduced onedimensional Brillouin zone are observed. An n-channel Si/SiGe MODFET demonstrates the device applications of this material concept.