The ion implantation is an usual technology to dope semiconductor crystals in the near-surface region. The incorporated dopands may strongly affect the electrical and optical properties of the material. The major side effect of the implantation of kinetic ions is the radiation damage.Lattice defects are formed, which disturb the intended crystal properties. This work contains a systematic investigation of the formation and the annealing behavior of the implantation induced damage in silicon and galliumarsenid as a function of the ion mass and the ion fluence. Mainly, the so-called vacancylike defects are observed, which form an attractive potential for the positively charged positrons due to missing atoms on regular lattice sites. The typical annihilation properties as well as the positron-diffusion data are used to characterize the defect types and the defect concentrations. The recent developments of the interpretation of the Doppler-broadened annihilation spectra are applied and comparisons with measurements obtained by Rutherford Backscattering, Raman- and infrared absorption-spectroscopy are done. The experimental data fit on qualitative and partial on quantitative models. In silicon, the implantation of boron ion induces different large vacancylike defects. In contrast, the generation of amorphous zones was obtained after implantation of heavy ions as silicon, phosphorous, or arsenic. The annealing behavior of the vacancy-type defects is characterized by processes of agglomeration and recombination of mobile point defects depending on their concentration. In amorphous layers of germanium, vacancylike defects after ion beam induced recrystalization were investigated. The processes of generation and annealing of defects after ion implantation in compound semiconductors are more complex. In galliumarsenid, the generation of vacancylike defects in the gallium sublattice was observed. Amorphous structures were obtained at high implantation fluences. The diffusion of defects behind the projected range was detected for undoped and n-type material. The formation of open-volume agglomerates was observed during the annealing of the weakly damaged material as well as during the recrystalization of the amorphous phase.