Surface diagnostics by ion scattering spectroscopy in gaseous environment

Nowadays, it is important to perform in-situ analysis of composition and thickness of ultra-thin (~5-50 A) surface layers in the course of the surface exposure to plasma or its components. For this aim, a new experimental facility based on the MEPhI Mass Monochromator is being developed, where low and medium energy ion spectroscopy of samples is used just after or during plasma exposure/ion treatment. A differentially pumped energy analyzer is used for recoil ion spectroscopy under grazing incidence conditions in the automated ion mass monochromator. A built-in Penning plasma source is used for plasma/ion treatment of samples. In this paper, the influence of the working gas (during the plasma source operation) on the energy spectra of reflected and recoil ions is studied. It is shown that the peak shape of the energy spectrum of scattered H+ ions increases during gas injection, and, at the same time, the signal intensity of the ionized recoils from the sample decreases. Nevertheless, analysis of the surface composition and thickness of the outer layer could be done at pressures ranging up to 10-4 Torr.