Study of the defect elimination mechanisms in aspect ratio trapping Ge growth

Recent research has demonstrated the effectiveness of the “aspect ratio trapping” technique for eliminating threading dislocations in Ge grown selectively in submicron trenches on Si substrates. In this letter, analysis of the mechanisms by which dislocation elimination is achieved has been carried out. Detailed transmission electron microscopy studies reveal that facets, when formed early in the growth process, play a dominant role in determining the configurations of threading dislocations in the films. These dislocations are shown to behave as “growth dislocations,” which are replicated during growth approximately along the facet normal and so are deflected out from the center of the selective epitaxial regions.