Modeling of threading dislocation reduction in growing GaN layers

In this work. a model is developed to treat threading dislocation (TD) redu ction in (0 0 0 1) wurtzite epitaxial GaN thin films. The model is based on an approach originally proposed for (0 0 1) FCC thin film growth and uses the concepts of mutual TD motion and reactions. We show that the experiment ally observed slow TD reduction in GaN can be explained by low TD reaction probabilities due to TD line directions practically normal to the film surf ace. The behavior of screw dislocations in III-nitride films is considered and is found to strongly impact TD reduction. Dislocation reduction data in hydride vapor phase epitaxy (HVPE) grown GaN are well described by this mo del. The model provides an explanation for the non-saturating TD density in thick GaN films. (C) 2001 Elsevier Science B.V. All rights reserved.