Significant quality improvement of GaN on Si(111) upon formation of an AlN defective layer

The stress state and crystal quality of a metal-organic chemical vapor deposition (MOCVD)-grown GaN film on a Si(111) substrate with different AlN buffer layer thicknesses were investigated. The properties of the AlN layers with varying thicknesses were studied. The three-dimensional growth mode with a rough surface of AlN on Si was observed. A defective layer with mixed orientations of AlN grains formed at the AlN/GaN interface. The AlN buffer layer with the defective layer accommodated most of the lattice mismatch between the GaN film and the Si substrate. The significance of the defective layer was proved by the obtainment of a 1 m thick nearly crack-free GaN film with high crystal quality.