Thermally stimulated relaxation of misfit strains in Si1−x Gex/Si(100) heterostructures with different buffer layers

The regularities of the defect formation in Si 1− x Ge x /Si heterostructures ( x = 0.15 and 0.30), consisting of a low-temperature Si buffer layer and a SiGe solid solution, during their growth and subsequent annealings at temperatures 550–650°C are investigated by the methods of optical and transmission electron microscopy and X-ray diffraction. It is shown that the misfit-strain relaxation by plastic deformation under the conditions studied occurs most intensively in heterostructures with low-temperature SiGe buffer layers. The maximum degree of misfit-strain relaxation (no higher than 45%) is observed in the heterostructures with x = 0.30 after annealing at 650°C. The results obtained are explained by the effect of the nature and concentration of dislocation-nucleation centers, existing in low-temperature buffer layers, on the characteristics of the formation of a dislocation structure in the heterostructures under consideration.