Overgrowth of GaN on GaN nanowires produced by mask-less etching

We report on the generation of GaN nanowires (NWs) using mask-less reactive ion etching (RIE). The NWs are believed to be the result of a high etching rate in regions where a high dislocation density is present in the GaN films grown on sapphire substrates. We have studied the effect of defect densities in the original GaN films and its relation to the generation of these NWs. We show that defect reduction in the overgrown GaN is related to the presence of a network of embedded voids generated between these nanowires during the regrowth on the etched nanowires. We show that further reduction in dislocation density can be achieved by repeating the process of nanowire generation and overgrowth. Also we report on the residual strain and curvature in GaN after the first and second embedded voids approach (EVA). ► Thick GaN films are etched without masks to form nanowires. ► Nanowires are attributed to preferential etching of specific defects. ► Etching and overgrowth on these nanowires is repeated twice on the same film. ► Repeatedly overgrown films of GaN show reduced defects and stress relief.