Initial stages of molecular-beam epitaxy growth of GaN on 6H-SiC(0001)

We studied the atomic H etching of 6H-SiC substrates and the initial stages of GaN/6H-SiC molecular-beam epitaxy growth. Atomic H etched 6H-SiC(0001)( Si) and (000 (1) over bar)(C) surfaces show a (root 3x root3)-R30 degrees a nd a (1x1) reconstruction respectively, with 0.7 +/-0.2 monolayers of remna nt O on both surfaces. GaN/6H-SiC(0001)(Si) growth is initiated by the form ation of islands that develop into flat-top terraces through coalescence. G rowth steps of one or integer numbers of the GaN atomic bilayer height are observed. GaN grown on 6H-SiC(000 (1) over bar)(C) is rougher with islands of irregular shape. X-ray photoemission spectroscopy studies show that Si 2 p and C 1s photoelectron inelastic mean free paths in GaN are 22 +/-1 and 2 0 +/-1 Angstrom, respectively. (C) 2001 American Institute of Physics.