@article{CTT100609237,
  author = {M. Sumiya and K. Yoshimura and T. Ito and K. Ohtsuka and S. Fuke and K. Mizuno and H. Koinuma and A. Ohtomo and M. Kawasaki},
  title = {Growth mode and surface morphology of a GaN film deposited along the N-face polar direction on c-plane sapphire substrate},
  journal = {Journal of Applied Physics},
  year = 2000,
}

@article{CTT100692177,
  author = {M. Sumiya and T. Ohnishi and K. Tanaka and A. Ohtomo and M. Kawasaki and H. Koinuma and K. Ohtsuka and S. Fuke},
  title = {Control of the polarity and surface morphology of GaN films deposited on C-plane sapphire},
  journal = {MRS Internet Journal of Nitride Semiconductor Research},
  year = 1999,
}