Lattice relaxation process of AlN growth on atomically flat 6H-SiC substrate in molecular beam epitaxy

The lattice relaxation process of AlN growth on an atomically flat 6H-SiC (0001)(Si) substrate was investigated by using high-resolution X-ray diffraction. The atomically flat 6H-SiC substrates were prepared by HCl gas etching at 1300degreesC. AlN layers were grown by molecular beam epitaxy using elemental Al and radio frequency plasma-excited active nitrogen. Owing to 1% in-plane lattice mismatch between AlN and 6H-SiC, lattice relaxation occurs at a certain thickness, which strongly affects the structural property of AlN layer, The layer thickness dependence of AlN c-axis lattice constant was examined. The structural property of these AlN layers is also discussed based on the linewidth of XRD omega-scan measurements. (C) 2002 Elsevier Science B.V. All rights reserved.