Normal-incidence Electron Gun alignment method for negative ion analysis on insulators by magnetic sector SIMS

J. Chen, S. Schauer, Richard Hervig

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


On Cameca magnetic sector SIMS (Secondary Ion Mass Spectrometer) instruments, detection of negative secondary ions during analysis of insulating materials represents one of the more challenging uses of the instrument. This is because the highest sensitivity is achieved using a positive Cesium primary ion beam to sputter a sample held at a negative potential. The combination of positive charge from the primary beam and the acceleration of negative ions from the sample surface results in the build-up of positive charge in the sputtered area. The Normal-incidence Electron Gun (NEG) is used to deliver electrons to neutralize the positive charge build-up. At typical conditions, the electron beam diameter is rather small (∼150 μm), so it is critical to align the NEG to overlay the analysis area as closely as possible. A new method has been developed to utilize cathodoluminescence of gallium nitride (GaN) to visually align the electron gun. This approach is shown to result in reproducible analyses of insulating phases, including depth profiling of oxide on semiconductor materials, bulk analyses for hydrogen, and oxygen isotope ratio microanalyses.

Original languageEnglish (US)
Pages (from-to)50-54
Number of pages5
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
StatePublished - 2013


  • Cathodoluminescence
  • Charge neutralization
  • Electron gun
  • SIMS

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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