Reduced structural anisotropy of (1122) semipolarGaN by using epitaxial lateral overgrowth

NonpolarGaN and semipolarGaN have been studied for minimization of quantum confined Stark effect in c-plane GaN. A (11 (2) over bar2) semipolarGaN layer was grown on m-plane sapphire substrates via epitaxial lateral overgrowth (ELOG) by metal organic chemical vapor deposition. Cross section filed emission scanning electron microscopy revealed a semipolarGaN layer with a smooth surface and an inverted trapezoid growth shape. For the layers not fully merged laterally, the structural anisotropic characteristics were reduced slightly. After merging laterally, the structural anisotropy was reduced significantly. In the [1 (1) over bar 00] directions of the X-ray beams, the full width at half maximum (FWHM) of the x-ray rocking curve of the (11 (2) over bar2) plane was 1195 arcsec for semipolarGaN on unpatterned template and the FWHM decreased to 468 arcsec for merged semipolarGaN by ELOG. In addition, the optical properties of (11 (2) over bar2) semipolarGaN using ELOG were improved significantly.