Comparison of surface morphologies in GaN films grown by rf-MBE and MOCVD on vicinal sapphire (0001) substrates

Surface morphologies of GaN films grown on vicinal sapphire (0 0 0 1) substrates by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) are investigated using atomic force microscopy (AFM). It is found that surface morphologies of GaN films depend not only on the vicinal angle and the inclination direction of the substrate, but also on the growth technique. However, the phenomenon concerning the surface step bunching during the growth is common and independent of the growth technique. Our experimental results give important hints to the precise control of the surface morphology in order to achieve high-quality device structures. (C) 2008 Elsevier B.V. All rights reserved.