The scattering of electrons from a boundary formed by ion implantation is discussed with reference to the lateral distribution of the implanted ions. A reduction in the lateral straggle is achieved by using channeled ions, but voids in the ion distribution still lead to the formation of a rough boundary. The specularity coefficient for such a boundary is measured using a transverse electron focusing device and the surface asperity parameter is calculated. It is shown that this value is significantly smaller than would be expected from the ion distribution and it is suggested that smoothing of the boundary is provided by the depletion around the implanted area.