Structural defects in GaN

Conventional and high resolution electron microscopy has been applied to study defects in both epitaxial and bulk GaN of wurtzite structure. Because of different growth conditions, epitaxial and bulk GaN crystalline materials differ in their defect structures. While stacking faults and dislocation loops associated with precipitates are typically observed in bulk GaN, dislocations are the major defect found in epitaxial GaN layers. Formation of stacking faults is equivalent to a wurtzite-zincblende structural transformation within a few basal planes and, hence, to a local change in symmetry.