Left: Top view (along ) of the relaxed core of the threading edge dislocation (b=1/3[1−210]). The three fold coordinated atoms 1 (Ga) and 2 (N) adopt a hybridisation similar to the (10−10) surface atoms. The distance between columns (1/2) and (3/4) is contracted by 9 % while the distance between columns (7/8) and (9/10) is stretched by 13 %. Right: High resolution Z-contrast image of a threading edge dislocation looking down . The bright dots are atomic columns of alternating Ga and N atoms. The dislocation core is shown in the boxed region. Y. Xin et al. .