GROWTH OF AN INVERSE TETRAGONAL DISTORTED SIGE LAYER ON SI(001) BY ADDING SMALL AMOUNTS OF CARBON

Si1-x-yGexCy layers have been grown on Si(001) substrates with molecular beam epitaxy and investigated with transmission electron microscopy and x-ray diffraction. We show that it is possible to adjust the strain in pseudomorphic SiGe layers by adding small amounts of carbon. A simple linear extrapolation between the different lattice constants opens the possibility to predict the SiGeC structure in dependence on the carbon content. It is possible to grown epitaxial SiGeC layers with up to 2% carbon. Larger carbon concentrations lead to a crystallographic degradation of the layers. We were able to grow the first pseudomorphic SiGeC layer on Si(001) that is under tensile stress. These layers exhibit a lattice plane spacing in growth direction smaller than that of silicon.