The redistribution of thep‐type dopant Be during the growth of GaAs and AlGaAs by molecular beam epitaxy has been studied using secondary ion mass spectrometry and capacitance–voltage carrier profiling. An asymmetric redistribution of Be toward the epitaxial layer surface has been observed in GaAs, along with a more symmetric diffusion in AlGaAs. The effects of Be concentration, growth conditions, and Fermi level on Be redistribution have been investigated. The long‐range asymmetric redistribution may be due to Be carried forward with the growth surface, while the more symmetric redistribution observed in AlGaAs is consistent with an interstitial–substitutional model for Be diffusion.