Analytical description of the sputtering yields of silicon bombarded with normally incident ions

Klaus Wittmaack
Phys. Rev. B 68, 235211 – Published 29 December 2003; Erratum Phys. Rev. B 69, 089901 (2004)
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Abstract

Experimentally determined sputtering yields of silicon bombarded with normally incident ions were analyzed with the aim of deriving a complete analytical description of the data. The yields, covering a wide range of energies (from 50 eV to 540 keV) and primary ions of vastly different mass (from H to Xe), can be described in universal form using (i) two energy-dependent functions, the reduced nuclear stopping cross section sn and Bohdansky’s threshold function η, (ii) a modified form of Sigmund’s α function, only dependent on the mass ratio of projectile and target atoms, and (iii) a constant calibration factor x0N/Es, where x0 is the effective mean escape depth of sputtered atoms, N the number density of Si atoms, and Es an effective surface binding energy. Considering the fact that according to computer simulations the mean escape depth increases significantly with increasing projectile energy, the observed constancy of x0N/Es requires the assumption that Es is not a constant but contains two terms, the “true” surface binding energy Es and an additional energy-dependent term presumably reflecting the fraction of deposited energy that is lost in inelastic processes as well as in creating phonons and damage. There are indications that the sputtering yields reported for H and D bombardment as well as for heavy-ion impact at very low energies are too small by factors up to about 2, presumably due to oxygen incorporation and/or growth of surface contamination layers under nonideal vacuum conditions.

  • Received 17 January 2003
  • Publisher error corrected 14 January 2004

DOI:https://doi.org/10.1103/PhysRevB.68.235211

©2003 American Physical Society

Corrections

14 January 2004

Erratum

Authors & Affiliations

Klaus Wittmaack

  • GSF-National Research Center for Environment and Health, Institute of Radiation Protection, 85758 Neuherberg, Germany

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Issue

Vol. 68, Iss. 23 — 15 December 2003

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