Realization of low-dislocation-density, smooth surface, and thick GaInN films on m-plane GaN templates

We grew thick Ga1−xInxN epitaxial films on GaN templates having different crystal orientations. Reciprocal space mapping of asymmetrical X-ray diffraction showed that 1.1-μm-thick Ga0.95In0.05N could be coherently grown on m-plane GaN, while those grown on a-plane and c-plane GaN showed partial relaxation. A 700-nm-thick Ga0.95In0.05N film with a threading dislocation density of approximately 1×108 cm−2 can be successfully grown on a GaN template using a grooved underlying layer. The mechanism of strain relaxation in c-, a- and m-plane Ga1−xInxN films is discussed.