AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA5
Effect of Annealing on the Crystallization of Ultrathin Al@sub2@O@sub3@ Film on NiAl(110)

Tuesday, November 5, 2002, 3:20 pm, Room C-112C

Session: Metal/Oxide Surfaces
Presenter: T.T. Lay, National Institute for Materials Science, Japan
Authors: T.T. Lay, National Institute for Materials Science, Japan
M. Yoshitake, National Institute for Materials Science, Japan
Correspondent: Click to Email
Al@sub2@O@sub3@ is a wide band gap insulator and it is reported that clear band gap exits in 0.5nm-thick well-ordered Al@sub2@O@sub3@ grown on NiAl(110).@footnote 1@ It has high potential of application in metal-insulator-metal(M-I-M) electron emitter which needs wide gap insulator. Oxygen dose rate, oxidation temperature and annealing are important parameters for well-ordered film. In our previous work, good crystalinity of Al@sub2@O@sub3@ layer was obtained by optimizing the dose rate and oxidation temperature.@footnote 2,3@ In the present work, change in crystalinity and surface composition due to annealing time is analyzed. NiAl(110) single crystal was put inside the UHV system and 1200L oxygen was introduced under pressure 5 x 10@super-7@ torr at 670K. After oxidation the specimen was annealed at 1070K. The oxide layer was amorphous before annealing and crystalline Al@sub2@O@sub3@ appeared after annealing. Crystal structure and surface composition were measured by LEED and XPS every hour during annealing. Intensity ratio of Al@sub2@O@sub3@ and NiAl spots was measured from LEED patterns. The intensity ratio is directly related to crystalinity and it increases linearly with annealing time. After 6 hours annealing, the ratio became saturated and there was less change by further annealing. The surface composition of O, Al and Ni changed only at the early stage of annealing and were almost constant one hour later. It is likely that the amount of oxygen contributed to well-ordered crystalline oxide is almost decided at oxidation. Annealing at 1070K for certain period of time is important for epitaxial growth of well-ordered oxide layer. @FootnoteText@ @footnote 1@ R.M. Jaeger, H.Kuhlenbech, H.J.Freund, M.Wuttig, W. Hoffmann, R. Franchy and H. Ibach, Surf. Sci., 259,235(1991), @footnote 2@ M. Yoshitake, B. Mebarki and Thi Thi Lay, Surf.Sci. Lett., in press., @footnote 3@ Thi Thi Lay, M. Yoshitake and B. Mebarki, J.Vac. Sci. Technol., submitted.