The progress made in the understanding of the role of threading dislocations in determining the properties of GaN and its alloys was reviewed. An increasing amount of work strongly suggested that threading dislocations in the group-III nitrides behaved as non-radiative recombination centres, had energy levels in the otherwise-forbidden energy-gap and acted as charged scattering centres in doped materials. When compared with III-V semiconductors, the relatively short minority carrier diffusion length (50nm) in the III-type nitrides, together with favourable threading dislocation geometries, minimized the dislocation-related degradation. The small value of the minority carrier diffusion length also permitted appreciable optical emission in materials with threading dislocation densities which were as high as 1010/cm2.

The Role of Threading Dislocations in the Physical Properties of GaN and its Alloys J.S.Speck, S.J.Rosner: Physica B, 1999, 273-274, 24-32