Dislocations formed under longitudinal stress field in epitaxial-lateral-overgrowth GaN

Dislocation semi-loops in the lateral epitaxial region of GaN have been observed and characterized using transmission electron microscopy. The loops are not coplanar in a (0 0 0 1) close-packed plane and the motion of vertical glide is found. The Burgers vectors are determined to be parallel to [0 0 0 1] direction. These evidences demonstrate that a c-axial stress field exists in the lateral region transited from the in-plane stress of the window region. The value and distribution of this special stress field have been measured via Auger electron spectroscopy.