We employed high-resolution double-crystal x-ray diffraction and transmission electron microscopy to characterize Si/Si1-xGe x strained-layer superlattices grown by ultrahigh vacuum/chemical vapor deposition technique. Rocking curve analyses showed uniform layer thickness and alloy composition across superlattices of 10 periods. Extensive dynamical x-ray simulation indicated that heterointerfaces were abrupt and the Si layer was found to be 206±5 Å thick and SiGe layer was 8.25% Ge and 185±5 Å thick. The thickness values were confirmed by the cross-sectional transmission electron microscopy. A tilt angle of 26 arcsec was observed between the (001) planes in the superlattice and the substrate, resulting from steps on the surface of 〈100〉 2° off oriented Si substrates.