AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS-MoP

Paper SS-MoP30
The Penetration Range of Low Energy (50-500 eV) Ar@super +@ and Kr@super +@ Ions Impinging onto a Graphite Surface Studied by the Oxidative Etching Method and STM

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: J.R. Hahn, Pohang University of Science and Technology, South Korea
Authors: J.R. Hahn, Pohang University of Science and Technology, South Korea
H. Kang, Pohang University of Science and Technology, South Korea
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Penetration of low energy (50-500 eV) Ar@super +@ or Kr@super +@ ions into a graphite surface results in the formation of surface vacancy defect (VD), formed by knock-out of carbon atoms, and interstitial defect (ID) where the incident atom is trapped between the carbon layers@footnote 1@, @footnote 2@, @footnote 3@. Thermal oxidation of the defected graphite surface etches away the carbon atoms surrounding a defect, leading to the formation of a pit of a large diameter and nearly circular shape. The etching process, when occurs from a defect of multi-layer depth, removes the carbons at and above the defect-containing layers simultaneously. Such phenomena enable us to locate the spatial position of the ion-generated defects by measuring the STM topography of the etched pits. The yield for production of multi-layer defect increases with ion collision energy. The depth distribution of the defect obtained by this method agrees well the result of theoretical trajectory calculation@footnote 1@. Lateral displacement of the incident ion inside the basal planes, upon penetration into the first carbon layer, is measured by STM from the distance between the VD and the ID formed in a pair. The average distance of the lateral travel varies with the incidence angle and the mass of ion. @FootnoteText@ @footnote 1@ W. Choi, C. Kim, and H. Kang, Surf. Sci., 281, 323 (1993). @footnote 2@ D. Marton, K. J. Boyd, T. Lytle, and J. W. Rabalais, Phys. Rev. B 48, 6757 (1993). @footnote 3@ J. R. Hahn, H. Kang, S. Song, and I. C. Jeon, Phys. Rev. B 53, R1725 (1996).