Transmission functions of an energy-mass spectrometer and energy spectra vs. emission angle data for silicon secondary ions

Results of a computer simulation of the propagation of ions through an energy mass analyzer comprising 90degrees and 180degrees spherical deflectors, transport lenses, and a quadrupole mass spectrometer are reported, which give the apparatus function of the analyzer for two operating modes. These functions were used to improve the experimental energy spectra for silicon secondary ions Si+, Si2+, and Si-2(+) measured under 10 keV Ar ion bombardment of a silicon surface. The observed shift of energy spectra maxima with angle of emission was explained in terms of the concept of a local electron excitation in the collision cascade region. This model, developed earlier for metals, was shown to adequately describe the principal regularities of the secondary ion emission from semiconductors. (C) 2003 Elsevier Ltd. All rights reserved.