Strain symmetrization effects in pseudomorphic Si1−yCy/Si1−xGex superlattices

We report on strain and stability measurements on pseudomorphic Si1−yCy/Si1−xGex superlattices which are synthesized by solid source molecular beam epitaxy on silicon (100) substrate. The strain in the superlattices alternates between tensile and compressive in the individual Si1−yCy and Si1−xGex alloy layers, respectively. A symmetrical strain distribution can be achieved directly on silicon by adjusting the carbon and the germanium content and/or the thickness of the individual layers. X-ray diffraction and transmission electron microscopy are applied to investigate the structural properties and the thermal stability.