Improved Analysis of Insulators in an ARL IMMA Using Positive Primary Ions and an Electron Gun

When analyzing insulating specimens by secondary ion mass spectrometry (SIMS) using positive primary ions as the bombarding species, a surface potential develops which partially or completely inhibits the extraction of ions into the secondary mass spectrometer. The result is that depth profiles, if measured intensities are observed at all, can be severely distorted, particularly when changes in composition lead to changes in conductivity of the specimen. Therefore surface charging limits the reliability of SIMS in analyzing insulators.