Johanna E. Raphael

Equilibrium Strain and Dislocation Density in Nitride Based Heterostructures

This work presents a computational approach for the determination of equilibrium strain and dislocation density in nitride-based heterostructures. Verification of this approach is demonstrated in the calculation of critical layer thickness for InxGa1-xN/GaN (0001) as compared to other work. The present modeling approach can also be applied to heterostructures of varying compositional profiles and structure. To demonstrate this, we studied the equilibrium strain and misfit dislocation density profiles for metamorphic InxGa1-xN/GaN (0001) heterostructures containing uniform layers on top of linearly-graded buffers. These structures were also compared to similar arsenide-based heterostructures involving InxGa1-xAs/GaAs (001) with the zinc blende crystal structure. The generalized energy minimization modeling tool presented here can be readily extended to arbitrarily graded nitride heterostructures with polar, semi-polar, or non-polar orientations.