Chemical ordering in wurtzite InxGa1-xN layers grown on (0001) sapphire by metalorganic vapor phase epitaxy

A diffraction analysis in the transmission electron microscope was carried out on InxGa1-xN layers grown on (0001) sapphire by metalorganic vapor phase epitaxy on top of thick GaN buffer layers. It is found that the ternary InxGa1-xN layers can be chemically ordered. The In and Ga atoms occupy, respectively, the two simple hexagonal sublattice sites related by the glide mirrors and helicoidal axes of the P6(3) mc symmetry group of the wurtzite GaN, The symmetry of the ordered ternary is subsequently lowered by the disappearance of these operations, and it is shown to agree with the P3ml space group. (C) 1998 American Institute of Physics. [S0003-6951(98)01714-8].