Anisotropic structural characteristics of (11(2)over-bar0) GaN templates and coalesced epitaxial lateral overgrown films deposited on (10(1)over-bar2) sapphire

a-plane GaN templates and coalesced epitaxial lateral overgrown (ELOG) films on r-plane sapphire substrates were investigated by x-ray diffraction (XRD). The a-plane GaN templates were found to have [0001]-oriented stripe-features, which is related to anisotropic mosaicity. For the mosaic blocks, the mosaicity reached the largest and the smallest values along the [1 (1) over bar 00] and the [0001] directions. The ELOG procedure with the SiO2 mask stripes perpendicular to the [0001] direction limits the preferable growth along this direction, and thereby enhances the [1 (1) over bar 00] growth. This leads to large-area, featureless, a-plane GaN films for which the wing tilt and not the fine mosaic block size becomes the major XRD line-broadening mechanism. (C) 2004 American Institute of Physics.