A model was developed to treat threading dislocation reduction in epitaxial (00•1) wurtzite thin films. The model was based upon an approach which had been proposed for (001) face-centered cubic thin-film growth, and used the concepts of mutual threading dislocation motion and reactions. It was shown that the experimentally observed slow threading dislocation reduction in GaN could be explained by low threading dislocation reaction probabilities due to the threading dislocation line directions being almost normal to the film surface. The behavior of screw dislocations in III-nitride films was found to affect strongly the reduction in threading dislocations. Dislocation reduction data on hydride vapor phase epitaxially grown GaN could be described well by this model. The model provided an explanation for the non-saturating threading dislocation density in thick GaN films.

Modelling of Threading Dislocation Reduction in Growing GaN Layers. S.K.Mathis, A.E.Romanov, L.F.Chen, G.E.Beltz, W.Pompe, J.S.Speck: Journal of Crystal Growth, 2001, 231[3], 371-90