| Research Abstract |
The aim of this research is to establish a new field of ion beam applications in solid state physics and material analyzes. Since the use of ion-induced secondary electrons for structure analysis is essentially an original approach, we have modified the whole system for electron measurements, including the electron spectrometer, in the first phase of the research.
The electron yield at energies between the loss-peak energy and the binary-peak energy, E_<B'> is contributed from all the target electorons (inner-shell, outer-shell, and valence electrons). Since under channeling incidence conditions the inner-shell electrons are completely shadowed except near the surface, valence and a few outershell electrons preferentially contribute to the observed yield. The reduced contrbution from inner-shell electrons should allow a sensitive analysis of the distribution of valence electrons in the crystal lattice.
With the shadowing analysis, the number of unshadowed electrons per target atom, N,has been determined from a comparison of the electron yields for H^+ and for He^<2+> of equal velocity. As the first trial of the shadowing analysis of bond electrons, measurements have been made for Si and Ge, of which the distribution of bond electrons is well known. The results indicate that for Si the value of N surely corresponds to the four bond electrons, while for Ge there is a considerable contribution from the outer-shell (3d) electrons. Furthermore, the value of N depends on the ion-flux distribution in the crystal channel. For precise analysis of bond electrons, a computer simulation approach in which the ion flux can be taken into account is now under way.
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