Reduction of dislocations in GaN epilayers using templated three-dimensional coherent nanoislands

Low-dislocation-density GaN layers have been grown on 6H-SiC(0001) substrates by molecular-beam epitaxy using high-density (similar to 4 x 10(11) cm(-2)) self-assembled Stranski-Krastanov GaN nanoislands buffer. The density of dislocations determined from hot-wet chemical etching and atomic force microscopy show that the insertion of coherent nanoislands as a buffer reduces the defect migration from the interface to the GaN epitaxial layers. The dislocation density is dramatically dropped to similar to 10(7) cm(-2) in GaN layers grown on coherent nanoislands as compared to similar to 10(9) cm(-2) in the typical GaN layers grown on the AIN buffer. (c) 2005 American Institute of Physics.