Dislocation filtering in semiconductor superlattices with lattice-matched and lattice-mismatched layer materials

Abstract

We investigate the ability of semiconductor superlattices to filter or block threading dislocations by growing and studying structural properties of superlattices composed of alternating layers (∼100 Å each) of InxGa1−xAs and InyAl1−yAs. These superlattices were grown with x=y corresponding to lattice-matched compositions such that the layers have minimal strain, and x≠y corresponding to lattice-mismatched compositions such that the layers have large coherent strains. By correlating the number of dislocations observed in optical images of the superlattices, with the amount of layer strain determined by x-ray double diffraction analysis, we investigate the effect of strain on the filtering ability. We find that both types of superlattices are effective in filtering dislocations.