Correlation of anisotropic strain relaxation with substrate misorientation direction at InGaAs/GaAs(001) interfaces

Abstract

We have investigated the effects of substrate misorientation towards (111)A, (111)B, and (011) on asymmetries in the strain relaxation of InxGa1−xAs, grown on (001) GaAs substrates by molecular beam epitaxy. For epilayers grown under conditions of two-dimensional growth, we find large anisotropies in bulk strain relaxation and epilayer rotation about an in-plane axis (epilayer tilt) in proportion to the degree of (111)A misorientation. The residual strain asymmetry is largest for the (111)A misoriented substrate (≳50%) and smallest for the (111)B misoriented substrate (<15%). At higher growth temperatures, the bulk strain relaxation becomes isotropic while the epilayer tilt remains sensitive to the offcut direction. At all temperatures, a preference for epilayer tilt toward the [110] direction for (011) misorientations is observed.