Mechanism of strain relaxation by twisted nanocolumns revealed in AlGaN/GaN heterostructures

Abstract

The structural properties of AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition on sapphire substrates with different thicknesses were studied by high-resolution x-ray diffraction. The relation between the deformations and dislocation densities in the layer and substrate was established. The dependence of the system’s curvature on the lattice mismatch, caused by different fractions of nanoblock twists with respect to the c-plane, was determined. A mechanism of elastic strain relaxation was proposed.