Fine structures and energy distribution of secondary electron emission from Si(111)

Abstract

Some secondary electron (SE) emission characteristics, i.e., total SE's, elastically and inelastically backscattered primaries, true SE's, and plasma loss spectra, of single‐crystal Si(111) were observed as a function of primary energy E_p. A small fraction of total SE's was introduced to a retarding field energy analyzer placed at 45° to the normally incident primary beam. As a result, a fraction of total SE's and of elastically backscattered (including diffracted) primaries showed quite similar fine structure even in detail, when observed as a function of E_p. By filtering a fraction of total SE's into individual energy ranges, the fine structures in true SE's were found at the same E_p's as in elastically backscattered primaries, but were in the opposite direction to the corresponding structures in the elastically backscattered primaries. On the other hand, the fine structures of inelastically backscattered primaries, i.e., energy‐loss primaries, showed quite a complex correlation to those of elastically backscattered primaries. It is concluded that the fine structures in σ (total SE yield) vs E_p and η (backscattering coefficient) vs E_p curves should be caused by the elastically backscattered primaries. The considerable number of electrons subjected to the surface and the first bulk plasma losses were found to be emitted from within a few atomic layers from the surface. Some problems on the Auger electron excitation are also discussed.