The role of point defects related to the presence of excess N was elucidated for InN thin films grown by different techniques. Elastic recoil detection analysis had shown the presence of excess N in state-of-the-art InN films. Using X-ray photoelectron spectroscopy and X-ray diffraction it was shown that two distinct forms of point defects could be distinguished; one of these appears to be an interstitial form of N, common in some forms of polycrystalline InN. The other was associated with a combined biaxial and hydrostatic strain observed for molecular beam epitaxy and chemical vapour deposition grown films, and may be a mixture of the N-on-metal antisite defect and lower densities of indium vacancies and interstitial N. The high density of defects present in all the InN samples examined suggests that stoichiometry related point defects dominate the electrical and optical properties of the material. The difference in the type of point defect observed for polycrystalline (rf sputtered) and epitaxial (molecular beam epitaxy and CVD) InN supports existing evidence that the Moss-Burstein effect was not an adequate description of the apparent band-gap difference between InN samples grown by different techniques.

The Nature of Nitrogen Related Point Defects in Common Forms of InN. K.S.A.Butcher, A.J.Fernandes, P.P.T.Chen, M.Wintrebert-Fouquet, H.Timmers, S.K.Shrestha, H.Hirshy, R.M.Perks, B.F.Usher: Journal of Applied Physics, 2007, 101[12], 123702