HREM and EDX studies of GaN as a guest material in the voids of synthetic opal

This paper demonstrates the synthesis of a 3D sublattice of GaN clusters directly in regularly distributed opal voids by embedding precursors followed by annealing in an ammonia atmosphere. HREM and EDX analyses were utilized to characterize these materials: wurtzite-type GaN clusters were indentified and these clusters were found to contain 2D defects (stacking faults). The specular reflectance from the (111) surface of the synthetic opal was measured and it was shown that the composites possessed photonic crystal properties.