The diffusion of arsenic and boron dopants resulting from rapid thermal annealing (RTA) in a tungsten-halogen lamp heater have been compared for implantations into 〈100〉 and 〈111〉 Si wafers. Random direction implantations have been performed for As, and random as well as channel implantations for B. The As profiles, measured by RBS, show no orientation dependence in inward diffusion. However, large differences in As out diffusion are observed above 1080°C, with the 〈111〉 cut crystal losing significantly more As than the 〈100〉 crystal. The B profiles, measured by SIMS, are practically the same for both Si orientations. They support the results of previous measurements which have shown that an initial fast diffusion occurs in the low concentration tail of the B profile. The major diffusion, however, takes place in the non-channeled part of the B distribution when annealing temperatures greater than 1000°C are employed. © 1985.