Films which had been grown by means of metal-organic chemical vapor deposition, onto c-sapphire substrates, were studied as a function of the post-growth rapid thermal annealing temperature (600C to 800C). Similar planar defects were observed in all of the heat-treated samples, and only their number density differed. It was demonstrated that there was a clear relationship between an improved crystalline quality, and post-growth high-temperature annealing. The number density of the near-surface defects was decreased by 61% as the annealing temperature was increased from 600 to 800C. The suppression of near-surface defects encouraged the development of a β-W2N interfacial phase, and promoted interface smoothness.

M.W.Cole, F.Ren, S.J.Pearton: Applied Physics Letters, 1997, 71[20], 3004-6