Mechanisms of misfit dislocation generation as well as peculiarities of dislocationstructure formation in Si0.7Ge0.3/Si multilayer heterostructures grown bymolecular beam epitaxy with low-temperature (LT) SiGe and (SiGe + Si) bufferlayers were studied. Full strain relaxation in the heterostructures with 200–250 nmthick buffer layers has been achieved. In the heterostructures with both types ofLT layer, misfit dislocation generation is found to proceed similarly toheterostructure growth at high temperatures; however, the rate of dislocationnucleation is higher due to the high vacancy concentration near the interface.Threading dislocations, which are not connected with misfit dislocationnetwork, are generated in the epitaxial layers apart from the SiGe–Siinterface to form a dislocation density of 107–108 cm−2 on the surface.