Superlattice-like stacking fault and phase separation of In_xGa_1-xN grown on sapphire substrate by metalorganic chemical vapor deposition

In_xGa_1-xN alloys were directly grown on sapphire substrate with a GaN nucleation layer. The degree of phase separation in the InGaN layer on sapphire substrate is maximized at higher growth temperature than for an InGaN layer grown on a thick GaN layer. For high indium composition, a superlattice-like stacking fault in the In_xGa_1-xN grown on sapphire substrate was detected by the selected area diffraction pattern and high-resolution transmission electron microscopy. The superlattice-like arrangement of stacking faults leads to the formation of split spots and the distance of split spots corresponds to the distance between stacking faults.