Doubly versus singly positively charged oxygen ions back-scattered from a silicon surface under dynamic O 2 + bombardment

Klaus Franzreb, Peter Williams, Jan Lörinčík, Zdeněk Šroubek

Research output: Contribution to journalArticle

Abstract

Mass-resolved (and emission-charge-state-resolved) low-energy ion back-scattering during dynamic O 2 + bombardment of a silicon surface was applied in a Cameca IMS-3f secondary ion mass spectrometry (SIMS) instrument to determine the bombarding energy dependence of the ratio of back-scattered O 2+ versus O + . While the ratio of O 2+ versus O + drops significantly at reduced bombarding energies, O 2+ back-scattered from silicon was still detectable at an impact energy (in the lab frame) as low as about 1.6keV per oxygen atom. Assuming neutralization prior to impact, O 2+ ion formation in an asymmetric 16 O→ 28 Si collision is expected to take place via 'collisional double ionization' (i.e. by promotion of two outer O 2p electrons) rather than by the production of an inner-shell (O 2s or O 1s) core hole followed by Auger-type de-excitation during or after ejection. A molecular orbital (MO) correlation diagram calculated for a binary 'head-on' O-Si collision supports this interpretation.

Original languageEnglish (US)
Pages (from-to)39-42
Number of pages4
JournalApplied Surface Science
Volume203-204
DOIs
StatePublished - Jan 15 2003

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Keywords

  • Doubly charged ions
  • Low-energy ion scattering
  • Molecular orbital
  • Oxygen
  • Si

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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