Identification of vacancy-impurity complexes in highly n-type Si

We show that the detailed atomic structure of vacancy-impurity complexes in Si can be experimentally determined by combining positron lifetime and ele ctron momentum distribution measurements. The vacancies complexed with a si ngle impurity, V-P and V-As, are identified in electron irradiated Si. The formation of native vacancy defects is observed in highly As-doped Si at th e doping level of 10(20) cm(-3). The defects are identified as monovacancie s surrounded by three As atoms. The formation of a V-As-3 complex is consis tent with the theoretical descriptions of As diffusion and electrical deact ivation in highly As-doped Si. [S0031-9097(99)08546-4].