The change of strain in Si0.7Ge0.3 films was investigated with medium energy ion scattering (MEIS). Si was removed in the films by selective oxidation at 800 degrees C, resulting in the formation of a Ge pile-up layer on the surface. The relaxation and the thickness of the pile-Lip layer were closely related to the oxidation time. MEIS data demonstrated that relaxation of the Ge layer in the depth direction occurred partially, and that the rates of relaxation decreased with depth. In addition, the rate of relaxation increased with the oxidation time. Lastly, the relaxation of the Ge layer affected the strain of the remaining Si0.7Ge0.3 substrate. (C) 2009 Elsevier B.V. All rights reserved.