Origin of the nonradiative 〈1120〉 line defect in lateral epitaxy-grown GaN on SiC substrates

Nonradiative line defects are observed by cathodoluminescence in 〈2̄110〉 directions in [11̄00]-oriented GaN stripes grown by lateral epitaxy on SiC substrates. Using transmission electron microscopy, the origin is determined to be principally screw dislocations. We observe the screw dislocations in vertically [0001] stacked configurations and forming dislocation loops and half loops contained in two of the three planes of the form {11̄00}. The dislocations are believed to serve to relax the anisotropic stresses experienced in the lateral epitaxy-overgrown stripes.