Surface morphology study of basic ammonothermal GaN grown on non-polar GaN seed crystals of varying surface orientations from m-plane to a-plane

GaN crystals were grown on hydride vapor phase epitaxy (HVPE) GaN seed crystals with non-polar surface orientations varying between on-axis m-plane and a-plane using the basic ammonothermal method. Three different surface morphology regimes were observed with the surface features including mounds, slate-like morphologies, and pyramidal 'spikes' composed of (0001) and non-polar microfacets. A macroscopic off-orientation of the non-steady-state surface and newly appearing steady-state growth surfaces towards [0001] by approximately 1 degrees was observed with geometric constraints suggesting an off-orientation of the observed {10-10} microfacets towards [000 (1) over bar] by approximately 1 or greater. (C) 2013 Elsevier B.V. All rights reserved.