Piezoelectric polarization associated with dislocations in wurtzite GaN

The piezoelectric polarization and its associated charge density are calculated for edge, screw, and mixed dislocations oriented parallel to the c axis in wurtzite GaN. It is shown that the polarization field generated by screw components of dislocations is divergence free, and thus does not generate electric fields. Edge dislocations produce polarization fields that have nonzero divergence only at interfaces. These characteristics minimize the electrical and optical effects of the dislocations mediated by the piezoelectric effect.