Dislocation behaviours in AlN and GaN films grown on vicinal sapphire (00▪1) substrates were investigated using transmission electron microscopy. It was found that the dislocation behaviour depended strongly upon the vicinal angle of the substrates. When the vicinal angle was 0.5°, the dislocation lines propagated along the c-axis and no bending of the dislocation line was found. On the other hand, dislocation bending occurred in films grown on 2.0°-off substrates, which resulted in a great reduction of the dislocation density in the films. Dislocation loop formation and the combination of two dislocations into one were the main mechanisms for this reduction. The surface morphology (mono-layer and multi-layer step formations) played an important role in determining the various dislocation behaviours.

Dislocation Behaviour in III-Nitride Epitaxial Films Grown on Vicinal Sapphire (0001) Substrates. X.Q.Shen, H.Matsuhata, H.Okumura: Physica Status Solidi C, 2006, 3[6], 1566-9