Small‐area [∼(50 μm)2], focused‐ion‐beam implantation of 25 keV Ga+in Si, Ge, InP, InSb, and ZnSe was investigated by experiments and by computer simulations. Specifically, the Ga concentration was determined for implantation fluences Φ ranging from 1×1014to 3×1017Ga+ions/cm2by means of secondary‐ion mass spectrometry. In all materials the Ga peak concentration exhibits an essentially linear increase with fluence up to some 1016cm−2; for higher values of Φ the Ga concentration tends to saturate. The saturation content of Ga at the surfacec∞ranges from ∼2 at % for ZnSe to ∼40 at % for Si. These values appear roughly inversely correlated with the specimens’ sputtering yields and agree thus with the predictions of a model of ion retention in the presence of concurrent sputter erosion. The computer simulations with the dynamic binary‐collision‐approximation codet‐dynproduce a fluence‐dependent evolution of the Ga concentrations in the examined semiconductors which is in qualitative agreement with the experiments. Furthermore, partial sputtering yields and the most probable ranges for 25 keV Ga+impact on the different materials have been determined both experimentally and from the simulation output.