A comparison of compositionally stepped and alternating step-graded structures, which were used in the production of relaxation buffer layers, was carried out by means of transmission electron microscopy. It was found that the latter was more efficient in relieving strain. The use of a simple balance force model made it possible to understand the greater generation of threading dislocations which occurred in alternating step-graded structures. It was suggested that these results could be used as design rules for buffer fabrication. However, they often differed from previously suggested rules; such as the so-called zero net strain concept of Dunstan  et alia.

D.Araújo, D.González, R.García, A.Sacedón, E.Calleja: Applied Physics Letters, 1995, 67[24], 3632-4