The Structural Evolution of Dot-Core GaN Substrates with Annealing Under Growth-Like Conditions

Abstract

Monochromatic X-ray topography was employed to study the structural evolution of c-plane dot-core GaN substrates with annealing under growth-like conditions at 1050°C for 10 hours. The measurements were performed at the 1-BM beamline of the Advanced Photon Source, Argonne National Laboratory using the (11_24) GaN asymmetric reflection to generate single exposure images (images exposed at a specific ω angular position along the X-ray rocking curve) as well as rocked images (a composite image exposed at many positions along the rocking curve). The anneal was found to flatten the lattice curvature both globally across the entire substrate as well as locally across and in between the individual cores. The radius of lattice curvature across the substrate changed from 17 ± 1 m to 27 ± 2 m after the anneal. The reduction in lattice curvature is indicative of a benefit of annealing on the structural characteristics of dot-core GaN substrates.