REAL AND RECIPROCAL SPACE MAPPING OF THE MOSAIC DISPERSION IN SELF-NUCLEATED ALXGA1-XN THIN-FILMS ON (00.1)SAPPHIRE

Measures of the mosaic dispersion of a series of self-nucleated AlxGa1 -xN thin films, grown by low-pressure metalorganic chemical vapor depo sition in a nitrogen carrier gas, have been accumulated by a combinati on of reciprocal space x-ray scattering patterns and real space images from scanning tunneling and atomic force microscopies. The films are shown to be dense mosaics of highly oriented islands whose in-plane an d out-of-plane orientational coherence and in-plane island size decrea se with increasing x. The highly correlated reductions in island size and orientational coherence are believed to be attributable to a decre ase in surface mobility of reactants, which is independent of nucleati on layer or carrier gas. (C) 1995 American Institute of Physics.