Inversion domains triggering recovery of luminescence uniformity in epitaxially lateral overgrown thick GaN film

A 150 mum-thick GaN layer was grown by halide vapor phase epitaxy utilizing selective lateral overgrowth on a SiO2-prepatterned sapphire substrate. A series of optically active regions above the SiO2 mask was observed in cros s sectional monochromatic cathodoluminescence images taken at 367 nm. These bright regions were, however, consistently terminated by triangular shaped domains at 60 to 80 mum thickness, leaving no sign of luminescence nonunif ormity beyond the thickness. In conjunction with the recent results on the characteristics of inversion domains in GaN, we proposed that these triangu lar regions might be inversion domains. (C) 2000 American Institute of Phys ics. [S0003- 6951(00)04651-9].