A model was developed for treating threading dislocation reduction in (00•1) wurtzite-phase epitaxial thin films. The model was based upon an approach which had originally been proposed for (001) face-centered cubic thin film growth, and involved 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 threading dislocation-line directions which were essentially normal to the film surface. The behavior of screw dislocations in III-nitride films was considered, and was found to strongly affect threading dislocation reduction. Dislocation reduction data on hydride vapor-phase epitaxially grown GaN were described well by the model. It also 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