Analysis of compositional uniformity in AlxGa1−xN thin films using atom probe tomography and electron microscopy

Calculated frequency distributions of atom probe tomography reconstructions (∼80 nm field of view) of very thin AlxGa1−xN (0.18 ≤ x ≤ 0.51) films grown via metalorganic vapor phase epitaxy on both (0001) GaN/AlN/SiC and (0001) GaN/sapphire heterostructures revealed homogeneous concentrations of Al and chemically abrupt AlxGa1−xN/GaN interfaces. The results of scanning transmission electron microscopy and selected area diffraction corroborated these results and revealed that neither superlattice ordering nor phase separation was present at nanometer length scales.