Material properties modification by high energy heavy ion implantation is a prospective technology leading to many device fabrications. This technique induces defects and hence the physical properties of the materials are modified. The effects of swift heavy ion implantation induced defects by 120 MeV 28+ Si ion implantation and doping in SI-GaAs are presented from the electron momentum distribution (EMD) of vacancy-type defects studied by two-dimensional angular correlation of annihilation

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... ation (2D-ACAR). The positron trapping due to the influence of high-energy Si-implantation in GaAs (n-type) is compared with the corresponding spectra of SI-GaAs and with Si-doped (n-type) GaAs. The EMD of the implanted sample shows a distinct increased isotropic distribution with a characteristic transform of its structure as evident from the low momentum region compared to the pristine sample. The characteristics of defects created by Si doping and by 120 MeV 28+ Si ion implantation of undoped semi-insulating (SI) GaAS are discussed. These results indicate the nature of positron trapping in open volume defects such as vacancy clusters created by implantation.