Origin of the nonradiative < 11(2)over-bar0 > line defect in lateral epitaxy-grown GaN on SiC substrates

Nonradiative line defects are observed by cathodoluminescence in [(2) over bar 110] directions in [1 (1) over bar 00]-oriented GaN stripes grown by la teral epitaxy on SiC substrates. Using transmission electron microscopy, th e 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 t he form {1 (1) over bar 00}. The dislocations are believed to serve to rela x the anisotropic stresses experienced in the lateral epitaxy-overgrown str ipes. (C) 2000 American Institute of Physics. [S0003-6951(00)03918-8].