The first measurements of subpicosecond dynamics of carrier capture and decay in Be &dgr;‐doped GaAs structures withp‐doping density ranging from 6×1012to 2×1014cm−2and spatial distribution on monolayer scale show that photoexcited carriers are captured in the &dgr;‐doped layer in <1 ps. Luminescence decay rates show a strong dependence on energy of the hole in the two‐dimensional Fermi gas. We attribute this to a change in the spatial electron‐hole overlap resulting from band‐mixing effects. We show that Be density fluctuations lead to strong carrier localization. ©1995 American Institute of Physics.