Evolution of strain throughout gallium nitride deposited on silicon carbide

During GaN growth on an on-axis SiC substrate, a large density of dislocations (∼10⁹ cm^-2) is unavoidably generated by the GaN/SiC misfit, uncontrolled misorientation in the substrate and defects present at the surface of the substrate. Recently a unique SiC substrate was developed with step-free and stepped mesas as well as continuous surface areas similar to a standard wafer all in close proximity. It is now possible to isolate the influence of defects and steps on the deposition of GaN on SiC. This paper provides a link between the dislocation environment and the strain state in the GaN film as well as the change of this strain with increasing thickness.