| AVS 58th Annual International Symposium and Exhibition | |
| In Situ Spectroscopy and Microscopy Focus Topic | Monday Sessions |
| Session IS+AS+SS-MoA |
| Session: | In Situ Characterization of Solids: Film Growth, Defects, and Interfaces |
| Presenter: | Junfa Zhu, University of Science and Technology of China |
| Authors: | J.F. Zhu, University of Science and Technology of China Q. Xu, University of Science and Technology of China S. Hu, University of Science and Technology of China X. Feng, University of Science and Technology of China D. Chen, University of Science and Technology of China |
| Correspondent: | Click to Email |
The growth and electronic structure of vapor-deposited Sm onto a well-ordered Al2O3/Ni3Al(111) ultrathin film under ultrahigh vacuum (UHV) conditions at room-temperature has been studied comprehensively using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM) and low electron energy diffraction (LEED). Our results indicate that at room temperature Sm grows in a layer-by-layer fashion for the first two layers, followed by three-dimensional (3D) growth. The interaction of Sm with Al2O3 thin films is so strong that deposited Sm is immediately oxidized at beginning. Both the oxidation states of Sm2+ and Sm3+ are found at low coverages (<1 ML) with the situation that the concentration of Sm2+ dominates below 0.2 ML and subsequently that of Sm3+ dominates. With increasing Sm coverage, the metallic state of Sm gradually appears. Annealing the film of 0.2 ML Sm/Al2O3 at T < 500 K results in further oxidation of the Sm species where all the Sm2+ species converts to Sm3+, Further annealing at higher temperatures leads to loss of Sm from the surface via subsurface diffusion.