Strain relief study concerning the In<i>x</i>Ga1−<i>x</i>As/GaAs (0.07&amp;lt;<i>x</i>&amp;lt;0.5) material system

Abstract

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&amp;lt;x&amp;lt;0.5. Cross-sectional transmission electron microscope observations indicate that for x&amp;lt;0.18, threading dislocations are absent in the epilayer and dislocations propagate from the heterointerface into the GaAs material, while, for 0.18&amp;lt;x&amp;lt;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.