Ar+ ion implantations on unpatterned and patterned GaAs/InGaAs samples were carried out to study the depth and the lateral spread of the damage profile. The photoluminescence emission intensity from quantum wells located at different positions in the layer structure was used as a local probe for the induced damage. An unexpected wide range of the damage profile is observed which can be explained in terms of accidental capture of ions into channels. Implantation along the axial channels of the zinc-blende crystal leads to an additional increase of the longitudinal damage range. It is shown that the lateral damage distribution under the implantation masks of ions implanted in a random direction is clearly broader than that of ions implanted along the [110] axis.