Experimental observation of the dislocation walls in heterostructures with two interfaces: Ge/Ge0.5Si0.5 10nm/Si(001) as an example

摘要

High-resolution electron microscopy (HREM) at the atomic scale has been applied to study the edge dislocation redistribution between interfaces in Ge/Ge0.5Si0.5/Si(001) heterostructures. Our results provide a direct explanation that plastic relaxation of the GeSi buffer layer proceeds owing to motion of Lomer-type dislocation complexes consisting of a pair of complementary 60 degrees dislocations with the ends of the {111} extra planes being located at a distance of similar to 2-12 interplanar spacings from each other. It is demonstrated that edge dislocations belonging to the upper and lower interfaces become arranged one under the other and dislocation walls are formed. The distributions of tension and compression in the [001] direction between two edge dislocations, obtained by processing the HREM image, testify to superposition of strain fields.