Photoemission spectroscopy of platinum overlayers on silicon dioxide films
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)
- Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08855-0849 (United States)
Soft x-ray photoelectron spectroscopy (SXPS) has been used to study ultrathin Pt films on silicon dioxide as model supported-catalyst materials. Using monochromatic synchrotron radiation. Pt 4f and Si 2p core level photoelectron peaks were measured as a function of platinum coverage in the range 0-10 ML. The bulk silicon and silicon dioxide film Si 2p peaks each show a binding energy decrease within the first ML of dosing. However, the effect is stronger for the silicon dioxide Si 2p peak, indicating an increased screening of the 2p electrons by the metal overlayer. We also observe a monotonic increase of the work function of the ultrathin film Pt/SiO{sub 2} system with coverage from 4.52 initially to 5.58 eV at {approx}10 ML. The Pt 4f{sub 7/2} core level binding energy decreased from {approx}72.2 to {approx}70.9 eV between 0 and {approx}10 ML coverage. This binding energy shift at low dose ({<=}1 ML), the coverage dependence of the Pt line shape and intensity, and the large saturation coverage for the work function are each consistent with two-dimensional cluster-island growth. The metallic nature of the Pt overlayer with dose is quantitatively verified by nonlinear, least-squares numerical fitting of the Pt 4f SXPS peak line shapes with Gaussian-broadened Doniach-Sunjic functions. (c) 2000 American Vacuum Society.
- OSTI ID:
- 20217193
- Journal Information:
- Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena, Vol. 18, Issue 4; Other Information: PBD: Jul 2000; ISSN 0734-211X
- Country of Publication:
- United States
- Language:
- English
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