Real-time x-ray-scattering measurement of the nucleation kinetics of cubic gallium nitride on beta-SiC(001)

We have performed a real-time x-ray-scattering study of the nucleation of cubic GaN on SiC(001) during metal-organic molecular-beam epitaxy. By monitoring both the Ga fluorescence and the diffracted intensity from the GaN film, we determine the growth rate and crystalline quality from submonolayer coverage to 350 nm. The results exhibit scaling behavior in the growth kinetics consistent with quasi-two-dimensional island growth. In this growth mode, three-dimensional nuclei form and then grow laterally until coalescence into a continuous film occurs. After coalescence, the growth rate drops to its steady-state value.