MECHANISMS OF SPUTTERED ATOMS ENERGY-SPECTRA FORMATION DURING EJECTION - COMPUTER-SIMULATION STUDY FOR 2-COMPONENT TARGETS

The process of collision cascade propagation has been investigated thr ough the solid-vacuum boundary for two-component targets: WSI MoSi and VSi. Simulations for ejection of 450 000 Si or W atoms from the surfa ce of WSi for cos theta(o)/E(o)(2) and 1/E(o)(2) initial distributions gave the maxima of the integral energy distributions of sputtered ato ms observed at 1.8 eV for Si and 3.4 eV for W in calculations with equ al binding energies for atoms of the light and the heavy components in good agreement with experiment. The surface mechanism of sputtered at oms of the components energy spectra formation based on stronger defle ction of light atoms towards the surface normal when scattering from h eavy neighbouring surface atoms during ejection was developed. The sur face mechanism was shown to be the alternative mechanism in formation of the observed maxima difference in respect to the difference in bind ing energies for atoms of components proposed by M Szymonski (Phys. Le tt., 1981, 82A, 203). The two-cone structure of ejection vs initial po lar angle for Si atoms sputtered was revealed and explained. Analysis gave a Si/W sputtering ratio equal to 1.29-1.55 (for 1:1: Si/W concent ration ratio at the surface) giving necessary addition to the Andersen -Sigmund formula which underestimated that ratio in comparison with av ailable experimental data. Copyright (C) 1996 Elsevier Science Ltd