Beschreibung:
<jats:p>Recent results have shown that nonlinearly graded buffer layers may be beneficial for the reduction of threading dislocation densities in metamorphic semiconductor devices. In this work, the authors have studied the equilibrium strain relaxation and misfit dislocation densities in nonlinearly graded heterostructures with logarithmic grading, and compare the cases of InxGa1−xAs/GaAs and GaAs1−yPy/GaAs buffer layers. The authors show that differences in the elastic stiffness constants give rise to significantly different behavior in these two commonly used buffer layer systems. Moreover, the width of the dislocated region, the average misfit dislocation density, and surface in-plane strain may be related to the nonlinearity coefficient of the grading profile.</jats:p>