Mg segregation at inclined facets of pyramidal inversion domains in GaN:Mg

Abstract

Structural defects in Mg-doped GaN were analyzed using high-resolution scanning transmission electron microscopy combined with electron energy loss spectroscopy. The defects, in the shape of inverted pyramids, appear at high concentrations of incorporated Mg, which also lead to a reduction in free-hole concentration in Mg doped GaN. Detailed analysis pinpoints the arrangement of atoms in and around the defects and verify the presence of a well-defined layer of Mg at all facets, including the inclined facets. Our observations have resulted in a model of the pyramid-shaped defect, including structural displacements and compositional replacements, which is verified by image simulations. Finally, the total concentration of Mg atoms bound to these defects were evaluated, enabling a correlation between inactive and defect-bound dopants.

Atomic-Scale Characterization of Extended Defects in Wurtzite GaN Heterostructures

“…Figure n shows such an IDB, where the 1 4 or 3 4 <0001> translation results from a mirror plane inserted along the hexagonal (0001) basal plane. Heavily Mg-doped , or Mg ion-implanted , GaN have been shown to form this defect type due to Mg incorporation at an apex, eventually developing into a translated inverted pyramid. The dotlike defect described by Iwata et al in Mg ion-implanted GaN, which has a similar 1 4 <0001> translation, may also take the form of this defect.…”