From a compilation of known literature, the substitutional fraction of boron in silicon is depicted in a diagram as a function of implantation dose and annealing temperature. Samples implanted at 1 1016 B/cm2 and annealed at 900, 1000 and 1100°C for 1 hour each are examined by the(n, α)method and compared to the RBS signal of the host atoms in various directions. Our results indicate a gradual transition from completely random positions after 900°C anneal to substitutional sites after 1100°C anneal.