Abstract: We investigate the characteristics of dislocation motion as influenced by defects in a low temperature buffer during the growth of lattice-mismatched heterostructures (SiGe/Si).To do this, we introduce a pair of 30. partial dislocation dipoles into a fully periodic Si crystal.Kinks and their combination with reconstruction defects (kink-RD), which trigger the dislocation motion, are produced in the dislocation line.We employ the Parrinello-Rahman method in a molecular dynamics (MD) simulation and find that shear stress is exerted on the model to evoke the 30°partial dislocation move.Eight stable configurations of left and right kink-RDs in one migration period are derived from the MD simulation, and the energy profile of the kinks and kink-RDs during the migration process are calculated by means of the nudged elastic band method with the Si tight binding potential.We find that the kink-RDs have a lower migration barrier than the kinks.Finally, we conclude that in the low temperature Si buffer technique, the low temperature hampers the motion of reconstruction defects and reduces their annihilation probability.Therefore, more kinks can combine with reconstruction defects to form kink-RD structures to promote the motion of 30°partial dislocation, thereby lowering the dislocation density needed for stress release in the heterostructures.

Key words: low temperature buffer, 30°partial dislocation, kink, reconstruction defect, dislocation motion, molecular dynamics