Extended X-ray absorption fine structure (EXAFS) of InN and InGaN

We present extended X-ray absorption fine structure (EXAFS) spectra of sputtered indium nitride films. Disorder in the In local environment has been analysed with the aid of a two-shell fit to data for samples grown at three different substrate temperatures. An excellent fit to a model comprising the first five shells of neighbours is obtained for the best sample. The results of this study aid a reinterpretation of EXAFS data on a set of seven InGaN layers, grown by metallorganic chemical vapour deposition (MOCVD), with a wide range of indium content. In addition, we measured the fundamental bandgaps and Urbach tailing parameters of both sets of samples by optical absorption spectroscopy and attempt to relate structure and composition to the optical properties of the films.