Silicon on insulator (SOI - Smartcut(R)) wafers were implanted with 1MeV and 300keV silicon ions to doses of 3.8x10(15) cm(-2) and 3x10(14) cm(-2), respectively, in order to modify the vacancy concentration in a controlled way. Boron was then implanted at 2keV to a dose of 1x10(15) cm(-2) into the near-surface part of the vacancy-engineered region. Atomic profiles were determined using SIMS and electrical profiles were measured using a novel Differential Hall Effect (DHE) technique, which enables profiling of electrically active dopants with a nanometer depth resolution. The electrical profiles provide pairs of carrier concentration and mobility values as a function of depth. The buried oxide (BOX) is proven to restrict the back diffusing interstitials positioned below the BOX from entering the silicon top layer and interacting with the boron profile. Also an increase of similar to50% in boron activation is achieved when a co-implant is used. However, SOI shows a reduced degree of activation when compared to bulk silicon, with or without a co-implant.