Strain evaluation in AlInN/GaN Bragg mirrors by in situ curvature measurements and ex situ x-ray grazing incidence and transmission scattering

Strain in lattice matched and mismatched AlInN/GaN Bragg mirror structures were studied by in situ curvature and various ex situ x-ray measurements. In the case of lattice mismatched structures considerable deviations of the in-plane lattice parameters were evidenced near the surface region as well as in depth using x-ray grazing incidence and x-ray transmission scattering in Laue geometry. The experimental findings are explained in terms of partial stress relaxation of the AlInN/GaN Bragg layer stack with respect to the underlying GaN buffer and a mutual tensioning of the GaN and AlInN layers with respect to each other.