The growth of digital Mn/GaAs heterostructures with high Mn sheet densities has been studied at widely varied As-4 pressures by in situ RHEED monitoring and microstructure characterization using TEM. In particular for hetero structures with a large number of periods, the evolution of the specular RHEED beam intensity can be advantageously used for growth control. Analysis of the influence of the Mn density and As-4 pressure on the ferromagnetic properties of the heterostructures suggests a correlation with intrinsic defects in the Mn sheets as well as in the GaAs spacers. Stacking faults are found to be the dominant growth defect. © 2005 Elsevier B.V. All rights reserved.