Annihilation phenomena of threading dislocations in AlN films grown on vicinal sapphire (00▪1) substrates were investigated by transmission electron microscopy. It was found that the dislocation density was greatly reduced when the AlN was grown on a 2°-cut vicinal sapphire substrate. Two different types of the annihilation mechanisms of threading dislocations were observed. One was the coalescence of 2 threading dislocations with opposite Burger's vectors b to form a dislocation loop with one b. The other was the formation of one threading dislocation from the combination of 2 threading dislocations with different Burger’s vectors, such as

[¯12▪0] + [2¯1▪0]  [11▪0]

These interactions between threading dislocations were caused by the formation of inclined threading dislocations, where the latter were locked and dragged by the macro-steps on the surface during growth.

Studies of the Annihilation Mechanism of Threading Dislocation in AlN Films Grown on Vicinal Sapphire (0001) Substrates Using Transmission Electron Microscopy. X.Q.Shen, H.Okumura, H.Matsuhata: Applied Physics Letters, 2005, 87[10], 101910 (3pp)