Plastic relaxation of GeSi/Si(001) films grown by molecular-beam epitaxy in the presence of the Sb surfactant

Plastically relaxed GeSi films with the Ge fraction equal to 0.29–0.42 and thickness as large as 0.5 μm were grown on Si (001) substrates using the low-temperature (350°C) buffer Si layer and Sb as a surfactant. It is shown that introduction of Sb that smoothens the film surface at the stage of pseudomorphic growth lowers the density of threading dislocations in the plastically relaxed heterostructure by 1–1.5 orders of magnitude and also reduces the final roughness of the surface. The root-mean-square value of roughness smaller than 1 nm was obtained for a film with the Ge content of 0.29 and the density of threading dislocations of about 10⁶ cm^?2. It is assumed that the effect of surfactant is based on the fact that the activity of surface sources of dislocations is reduced in the presence of Sb.