300nm-thick AlN layers without a nucleation layer were grown onto 6H-SiC (00•1) vicinal substrates with 3-bilayer-height steps by rf-plasma-assisted molecular-beam epitaxy. A Ga beam was supplied for 0 to 30s, just before the growth of AlN. The Ga pre-irradiation for 7 seconds (∼1.6ML) was found to be effective for realization of the AlN layer-by-layer growth mode at an earlier stage of the growth and reduction of threading dislocation densities in the AlN layers. The screw-type and edge-type threading dislocation densities were ∼106 and 6 x 108/cm2, respectively.

Enhancement of Initial Layer-by-Layer Growth and Reduction of Threading Dislocation Density by Optimized Ga Pre-Irradiation in Molecular-Beam Epitaxy of 2H-AlN on 6H-SiC(0001). H.Okumura, T.Kimoto, J.Suda: Physica Status Solidi C, 2010, 7[7-8], 2094–6