Performance Of A Bragg Ionization-Chamber For Depth Profiling And Surface-Analysis

The application of Bragg-curve spectroscopy to ERD and RBS is described. In particular, the performance for depth profiling and surface analysis is investigated. Advantages and limitations are discussed. Typical results are good selectivity of the atomic charge number Z up to 20 with a depth resolution on the order of 10 nm and submonolayer sensitivity. An important advantage is the possibility of combining in one measurement the spectroscopy of recoil ions and scattered projectiles. The method is limited by the condition that the energy of the detected particles should be within the operative region of a nearly constant Bragg-peak height. An estimate of this low-energy limit is derived. The low background in the operative region allows the analysis of profiles down to concentrations of about 0.01% of the stoichiometric ones. For different ions the energy calibrations were found to differ by about 3%. The basic ideas and preliminary results of a quantitative analysis of depth profiles are described.