The redistribution of Be in highly doped AlxGa1−xAs layers and AlxGa1−xAs/AlAs(GaAs) short period superlattices (SPSL) during molecular beam epitaxy was investigated by secondary ion mass spectrometry (SIMS) depth profiling. Be outdiffuses significantly from these layers and, additionally, segregates in growth direction. Conversely, Be is depleted and incorporated only up to a solid-solubility limit depending on the Al content. SPSLs with shorter period are disordered and show the solid-solubility limits of homogeneous AlxGa1−xAs layers with the same average composition. Be solid-solubility limits in AlxGa1−xAs layers covering the whole range from GaAs to AlAs are derived from the SIMS depth profiles.