Initial stage of GaN nucleation on √3 x √3 R30°-Ga reconstructed 4H-SiC(0001)Si by molecular-beam epitaxy

Gallium nitride (GaN) initial nucleation kinetics by the influence of SiC(0001)(si) surface structure has been investigated. The Ga induced root3 x root3 R30degrees and 3 x 3 surface reconstructions are found to be more efficacious for GaN growth. During the initial stage of GaN/4H-SiC(0001)(si) growth by molecular-beam epitaxy, coherent polygon islands grow wide (similar to40 nm) along the lateral directions. These coherent islands develop 2D growth through early coalescence as evidenced by the in situ reflection high-energy electron diffraction observation. The control of Ga-adatom migration and the adsorption of 1/3 and 1 monolayer (ML) of Ga-adatom govern the surface morphology of the GaN layers. The bulk surfaces of (1 x 1) and (2 x 1) introduces incoherent nuclei, resulting in a delay of GaN coalescence, exhibits rough growth front and poor surface morphology. (C) 2003 Elsevier Science B.V. All rights reserved.