Strain relief study concerning the InxGa1−xAs/GaAs (0.07<x<0.5) material system

The evolution of dislocations in the InxGa1−xAs/GaAs material system has been studied as a function of the ternary alloy comparison in the range 0.07<x<0.5. Cross-sectional transmission electron microscope observations indicate that for x<0.18, threading dislocations are absent in the epilayer and dislocations propagate from the heterointerface into the GaAs material, while, for 0.18<x<0.28, dislocations appear to propagate into both the epilayer and the GaAs. Furthermore, for x ≳0.28, all the dislocations are observed in the epilayer while the GaAs appears to be dislocation-free. We propose a model involving the balance of forces acting on misfit dislocations generated at the heterointerface which includes a surface image force term to explain our observations of dislocation evolution as a function of the ternary alloy composition.