Stress in silicon interlayers at the SiO_x/Ge interface

Materials such as germanium display an advantage relative to silicon in terms of carrier mobilities but form poor quality interfaces to oxides. By sandwiching silicon layers between a germanium substrate and the oxide, advantages of the silicon oxide/silicon (Si Ox Si) interface can be retained combined with the advantage of a high mobility germanium substrate. Using density functional theory calculations, stress within the silicon interlayer is quantified for different interlayer thicknesses revealing that for up to three silicon layers, the stress in the interlayer is compensated for by the energy gained by forming silicon-oxygen bonds at the interface.