Quantitative analysis with heavy ion E-TOF-ERD

Abstract

Moderate-velocity heavy ion TOF-ERD combined with energy detection (E-TOF-ERD) is a powerful analytical technique, with large cross sections (∼10 −21 cm 2/sr), high depth resolution (∼2 nm), and good mass resolution (∼1 amu). Measurements on several oxides were performed with the E-TOF-ERD system at Sandia National Laboratories using 10–15 MeV Au and 6.5 MeV I incident beams. Commercially available multi-parameter acquisition software was used for data collection. Quantitative information about the composition of the oxide samples was obtained by converting the time domain spectra into the energy domain and analyzed with the computer simulation code, SIMNRA. Use of these acquisition and simulation software codes will be discussed. Several problems associated with the use of moderate-velocity heavy ion E-TOF-ERD were identified during measurement and analysis of the oxide samples. These include (1) difficulty in accurately measuring the beam dose, (2) unreliable tabulated stopping powers for heavy ions, and (3) erosion of some thin oxides by Coulomb explosions caused by the beam. These problems are also discussed.