The energy spectra of secondary ions emitted during ion bombardment

Abstract

Abstract Secondary ion energy spectra have been measured for singly charged ions emitted from targets irradiated with 43 keV A+ ions. Targets studied include the 3d transition metals (Sc, Ti, V, Cr, Fe, Ni) Cu and Zn, Zr, Al and Si and the compounds SiO2, Al2O3, NaCl, KCl. Energy spectra were measured in the energy range 1–600 eV. In several cases a peak in the energy spectrum in the region around 200 eV has been found. This is in addition to the usual low energy peaks in the region of 5–10 eV. In many cases the low energy peak was observed to decay steadily with irradiation time or to increase with oxygen pressure. In the case of the cleanest Zn spectrum, only the high energy peak can be detected. The data are discussed in relation to current models of secondary ion emission. We conclude that, in general, elemental metal targets which are clean are characterised by the high energy peak in the secondary ion energy spectrum. The slower ions emitted have been neutralised by electron exchange processes. The ...