A stressed MOS device and a method for its fabrication are provided. The MOS device comprises a substrate having a surface, the substrate comprising a monocrystalline semiconductor material having a first lattice constant. A channel region is formed of the monocrystalline silicon material adjacent the surface. A stress inducing monocrystalline semiconductor material having a second lattice constant greater than the first lattice constant is grown under the channel region to exert a horizontal tensile stress on the channel region.