INFRARED AND TUNNELING SPECTROSCOPY STUDY OF AIN FILMS PREPARED BY ION-BEAM DEPOSITION

Aluminum nitride films ranging in thickness from 0.4 to 25 nm were prepared by reactice ion-beam sputter deposition, utilizing a pure aluminum metal target and both pure nitrogen and 25% hydrogen-enriched nitrogen plasma. The 0.4-1.5 nm AlN films were studied by inelastic electron tunneling spectroscopy. Complementary vibrational techniques, specular reflectance and absorbance FT-IR spectroscopy, were used to analyze the thicker insulating films. The principal component of the insulating layers is AlN. Al-H, Al-N2, and NHx surfaces species are also present as minor components. Tunneling spectroscopy showed superior sensitivity over the optical methods in identifying various components of the AlN films. The quality of the tunneling barrier is enhanced by the presence of H2 during the AlN deposition.