The diffusion behavior of ion-implanted arsenic in strained Si/relaxed Si0.8Ge0.2 structures is studied during rapid thermal processing in oxygen (interstitial injection) and ammonia (vacancy injection). During rapid thermal processing in an oxygen ambient, arsenic diffusion in SiGe is reduced, while an ammonia ambient produces strong enhancement, especially for short times. The results suggest that arsenic diffusion in SiGe has a stronger vacancy component than arsenic diffusion in Si. Vacancy injection is also observed to enhance the diffusivity of Ge from relaxed SiGe into strained Si. (C) 2003 Published by Elsevier B.V.