Strained‐layer structures consisting of ∼30–35 nm Si1−xGex(x=0.16–0.29) and 33 nm Si deposited by molecular beam epitaxy on a (100)Si substrate have been amorphized by ion implantation at 40 K with 120 keV As+. Rutherford backscattering/channeling measurements using 2 MeV He+ions have been used to measure the thickness of the amorphous layer and monitor the subsequent epitaxial regrowth occurring as a result of annealing at 560–600 °C. Angular scans across the {110} planar channels indicate that the initial crystallinity and strain was recovered forx=0.16; however, forx=0.29 crystal quality was greatly reduced and the coherency at the substrate‐alloy layer interface was destroyed.