MBE basic growth mechanisms for III–V compounds on (100) surfaces, step flow and 2D nucleation, are shown to be modified by a periodic modulation of the molecular beams in synchronism with the layer-by-layer growth sequence characteristic of optimized MBE. Beam modulation is shown to enhance nucleation on completed monolayers, leading to a better 2D or layer-by-layer growth (NEMBE). The possibility of growing in a kind of atomic layer-by-layer mode (ALMBE) is studied by optical (RDS) and RHEED in-situ analysis. Applications to the growth of III-V A-V B pseudoalloys and III AV B-III CV D superlattices and heterostructures are presented. Finally, exploratory growth experiments on low index surfaces (311), (211)A, (211)B, (111) and (110) by using modulated beams are discussed.