The atomic structure and properties of wurtzite GaN epitaxial layers

Structural investigations show that extended defects in GaN have multiple atomic configurations. The pure edge threading dislocations exhibit 5/7, 4 or 8 atom cycles along their line. The dislocations are now known to have a strong effect on the transport as well as on the optical properties of the layers. The basal stacking faults (I1, I2 and E) form mostly close or inside the buffer layer. They were shown to be associated with photoluminescence peak close to the conduction band minimum (3.425 eV). The prismatic stacking fault bears two atomic configurations 1/2 〈101&#x0304;1〉 and 1/6 〈202&#x0304;3〉 whose stability is different in GaN, AlN or InN. The {101&#x0304;1} inversion domains which cross the whole epitaxial layers occur in particular growth conditions, they exhibit two surface morphologies and ranges of size. The smaller ones (<20 nm) terminate on a flat surface, they contain wrong bonds inside the boundary planes. The large ones (50 nm) are pyramid topped and their boundaries are reconstructed.