GaN/AlxGa1−xN superlattices with different period thicknesses tp were grown as interlayers between GaN and AlyGa1−yN epilayers. The effect of threading dislocations blocking became more evident with increasing tp. Transmission electron microscopy analysis shows that threading dislocations were inclined to be bent in superlattices and terminated in GaN wells as a result of strain. X-ray diffraction measurement also validated that GaN wells played a more important role as a threading dislocations filter. The blocking of threading dislocations in superlattices resulted in an abnormal decrease in relaxation factors with increasing tp.

Study on Threading Dislocations Blocking Mechanism of GaN/AlxGa1−xN Superlattices. L.W.Sang, Z.X.Qin, H.Fang, X.R.Zhou, Z.J.Yang, B.Shen, G.Y.Zhang: Applied Physics Letters, 2008, 92[19], 192112