Role of Ga flux in dislocation reduction in GaN films grown on SiC(0001)

GaN films are grown by plasma-assisted molecular-beam epitaxy on SiC substr ates. The width of the x-ray rocking curve for the (10 (1) over bar2) refle ction exhibits a distinct minimum for Ga/N flux ratios which are only sligh tly greater than unity. Correlated with this minimum, the surface morpholog y is somewhat rough, with a hill and valley topography. Based on transmissi on electron micrographs, the reduction in rocking curve width is attributed to enhanced annihilation of edge dislocations due to their tendency to clu ster at topographic valleys. (C) 2001 American Institute of Physics.