Direct imaging of the valence electronic structure of solids by (e,2e) spectroscopy

The spectral momentum density ϱ(E, q ) of the valence electrons of solid thin films of annealed amorphous carbon, amorphous silicon and silicon carbide has been measured using (e,2e) spectroscopy. Substantial contrast has been observed between the images of the three momentum densitites, which show not only well-defined energy band dispersion in the three materials, but also the antisymmetric gap due to the unequal potentials between the Si and C sites in the silicon carbide. The relation between the three momentum densities is explained within the framework of the one-electron band theory of solids.