ELECTRON-MOMENTUM SPECTROSCOPY OF CRYSTAL SILICON

Electron-momentum spectroscopy based on the (e,2e) reaction has been u sed to observe the energy-momentum density of valence electrons in the [110] direction for an ultrathin, free-standing film of crystalline s ilicon. An asymmetric scattering geometry is used in which the inciden t, scattered and ejected electron energies are 20.8, 19.6, and 1.2 keV , respectively. The measurement is complicated by the possibility of d iffraction of the free electrons. The theory of the reaction including diffraction is summarized and applied to experiments with different t arget orientations. The orientation is determined from an independent electron diffraction experiment. Very good agreement between theory an d experiment is observed.