The distributions of Bi ions implanted into the double‐layer structures Si/Ge, Ge/Si, C/Si, and C/Ge have been determined using MeV He backscattering techniques. A discontinuity of the backscattering yield was found in the Bi spectrum at or near the energy corresponding to the interface between film and substrate. In each case the magnitude of the interface discontinuity in the ion concentration, which was derived from this backscattering yield, coincided with the theoretical predictions within the experimental error of 20%.