The role of point defects related to the presence of excess nitrogen is elucidated for InN thin films grown by different techniques. Elastic recoil detection analysis has shown the presence of excess nitrogen in state-of-the-art InN films. Using x-ray photoelectron spectroscopy and x-ray diffraction it is shown that two distinct forms of point defects can be distinguished; one of these appears to be an interstitial form of nitrogen, common in some forms of polycrystalline InN. The other is associated with a combined biaxial and hydrostatic strain observed for molecular beam epitaxy(MBE) and chemical vapor deposition (CVD) crown films, and may be a mixture of the nitrogen-on-metal antisite defect and lower densities of indium vacancies and interstitial nitrogen. 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 (MBE and CVD) InN supports existing evidence that the Moss-Burstein effect is not an adequate description of the apparent band-gap difference between InN samples grown by different techniques.
Copyright 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of applied physics, Vol. 101, Issue 12, pp.123702-1-123702-11, and may be found at http://link.aip.org/link/?jap/101/123702.