ABSTRACT
Nucleation images of GaN buffers grown by metalorganic chemical vapor deposition (MOCVD) on (001) GaAs substrates were obtained by atomic force microscopy (AFM) and were employed to investigate the growth temperature and time dependence of the nucleation mechanisms. The growth mode corresponds to 2D island nucleation at low temperatures, while 3D island growth is observed at high temperatures. Large grain sizes and good surface coverage was obtained for 3min growth. Optimum criteria were established for buffer growth and 0.5μm thick GaN films were grown on different buffers for comparison. Their morphology and phase dependence on nucleation layer characteristics are discussed. Theoretical modeling by Monte-Carlo techniques compliments these studies.
