Growth of ultra-thin AlN(0001) films on NiAl(111)

The growth of ultra-thin AlN films on NiAl(111) has been studied by means of high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). The AlN films were grown upon adsorption and thermal decomposition of NH3 on NiAl(111). HREEL spectra of the ordered AlN film show a Fuchs-Kliewer phonon mode at 860 cm(-1). This is in good agreement with theoretical spectra calculated on the base of the dielectric theory. The electronic energy gap of the thin AlN films is determined to be E(g) congruent to 6.0 +/- 0.2 eV. In addition, interface gap states at 1.1 and 5.1 eV were found. The well-ordered AlN film renders a distinct LEED pattern, which exhibits hexagonal symmetry. The film grows in AlN[0001]\\NiAl[111] direction.