Surface morphology of GaN layer grown by plasma-assisted molecular beam epitaxy on MOCVD-grown GaN template

We performed the epitaxial growth of the GaN layer on MOCVD-grown GaN templates by plasma-assisted MBE (rf-MBE). We investigated the surface morphology and the growth-mode mechanism, varying the growth condition such as the growth rate and the growth temperature. By reducing the growth rate from 0.5 mum/h to 0.2 mum/h, smooth and flat surface was achieved. The rms surface roughness of 0.2-mum/h-GaN films was smaller than that of MOCVD templates. The cause of smooth surface morphology was the restriction of the spiral growth. Moreover, by changing Ga-flux at 0.2-mum/h growth condition, we found that it was important for smooth surface morphology to grow in stoichiometric condition as well as low growth rate. (C) 2003 WILEY-VCH Verlag GmbH & Co, KGaA, Weinheim.