High‐resolution x‐ray reciprocal space mapping was employed to determine the in‐depth strain distribution of Si1−xGexfilms with linear composition gradings between 4.2% and 15% Ge per &mgr;m, and thicknesses between 0.4 and 1.7 &mgr;m. The variation of grading and thickness parameters of the samples provides a complete picture of the overall relaxation behavior of linearly graded epilayers. The x‐ray data show a top layer of grading‐dependent residual strain whereas the lower parts of the films are completely and/or partly relaxed with respect to the Si substrate. ©1995 American Institute of Physics.