ABSTRACT
In recent years the strain relaxation of (001) InGaAs layers has become relatively well understood. In contrast, little progress has been made for the alternative (111) substrate orientation. A study of InxGa1-xAs/GaAs (111) B single quantum wells by transmission electron microscopy has shown that, for low indium content samples (x <0.25), plastic relaxation takes place by the formation of a 60° misfit dislocation (MD) network. However, when the indium content is increased (x >0.25) a new MD network develops. Microscopy results show that this new MD configuration is strongly dependent on the direction of substrate misorientation. These observations indicate that surface steps play a fundamental role in the strain relaxation mechanism for such high indium content heteroepitaxy.
