FORMATION OF THIN ALN FILMS ON NIAL(001) UPON THERMAL-DECOMPOSITION OF AMMONIA

The formation of thin AlN films on NiAl(001) has been studied by means of high resolution electron energy loss spectroscopy (HREELS), low-energy electron diffraction (LEED), and Auger electron spectroscopy. The AlN films were grown by the adsorption of NH3 on NiAl(001) at T=80 K and subsequent thermal decomposition at elevated temperatures. After annealing to T=1250 K, a distinct LEED pattern appears which exhibits pseudo-twelvefold symmetry. This indicates the formation of two hexagonal domains of AlN which are rotated by 90°with respect to each other. HREEL spectra of the ordered AlN film show a Fuchs-Kliewer phonon mode at 865 cm-1 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≅6.1 eV. © 1995 American Institute of Physics.