Local density-functional methods were used to examine the behavior of O and O-related defect complexes on the walls of nanopipes. It was found that O had a tendency to segregate to the (10•0) surface. The Ga vacancy surrounded by three O impurities, [VGa-(ON)3], was identified as being a particularly stable and electrically inert complex. It was suggested that, when inter-island spaces shrank during Stranski-Krastanov growth, these defects reached a critical concentration; beyond which further growth was prevented and nanopipes formed.

Effect of Oxygen on the Growth of (10¯10) GaN Surfaces: the Formation of Nanopipes. J.Elsner, R.Jones, M.Haugk, R.Gutierrez, T.Frauenheim, M.I.Heggie, S.Oberg, P.R.Briddon: Applied Physics Letters, 1998, 73[24], 3530-3