Characterization of aluminium nitride nanostructures by XANES and FTIR spectroscopies with synchrotron radiation

We investigated different AlN nano-systems using spectroscopic methods. Experiments were performed at the Synchrotron Radiation Facility of the Laboratori Nazionali di Frascati using both XANES (x-ray absorption near edge spectroscopy) and FTIR (Fourier transform infrared spectroscopy) techniques in order to investigate materials with both interesting tribological and electronic properties. Comparisons have been performed between measurements by standard x-ray diffraction (XRD) and x-ray absorption (XRS) at the K-edge of Al, a spectroscopy method sensitive to the local order and correlated to the local and empty density of states of this wide band-gap semiconductor. Preliminary XAS simulations at the Al K edge are also presented. Correlations between XRD and XAS have been drawn, since x-ray absorption reveals structural information complementary to that addressed by x-ray diffraction. Moreover, a comparison has been performed by infrared (IR) absorption both in the mid- and in the far-IR ranges between different AlN forms: namely, powders, nanoparticles and nanotubes. Data clearly show changes connected with the electronic properties and the optical phonon modes of AlN nano-systems.