[en] Thick, linearly graded-composition strained Si_1-xGe_x/Si layers were recently developed for proton beam bending and extraction experiments. Such unrelaxed layers which are many microns thick necessitate a low maximum germanium content. Here, graded Si_1-xGe_x epilayers, 5-20 μm thick with maximum Ge compositions of x=0.5-1.7%, grown by low energy plasma enhanced chemical vapour deposition were characterized using a recently developed mode of ion channeling analysis which is capable of quantifying the small lattice rotations along off-normal planar directions. High-quality 10 μm Si_1-xGe_x epilayers with bend angles along off-normal directions which agree very well with those of fully strained layers are successfully grown