A structural assessment of various interfaces formed between successive GaN/AlN layers epitaxially grown on (00•1) sapphire, as well as between n-type and p-type GaN was presented, using transmission and high-resolution electron microscopy. The structure of the interfaces between the thick GaN and the thin AlN interlayers was investigated in terms of misfit difference and elastic fit of the 2 crystal lattices. Dense threading dislocations were observed to originate from the substrate/buffer layer interface and their interaction with the successive AlN interlayers was studied. Furthermore, basal inversion domain boundaries localized in the n-GaN/p-GaN interface were evaluated.

Interfacial and Defect Structures in Multilayered GaN/AlN Films. P.Komninou, T.Kehagias, J.Kioseoglou, G.P.Dimitrakopulos, A.Sampath, T.D.Moustakas, G.Nouet, T.Karakostas: Journal of Physics - Condensed Matter, 2002, 14[48], 13277-83