Photoemission measurements of the valence levels of amorphous SiO2

The complete valence band in amorphous SiO2 has been examined by photoelectron spectroscopy at photon energies of 21.2, 26.9, 40.8, and 1486.6 eV. The spectra show emission from an 11.2-eV-wide p-derived valence band and from the oxygen 2s level at 20.2 eV below the valence-band edge. Four pieces of structure in the p bands are related to the single bonding and the two nonbonding orbitals of the O - ion. A narrow, nonbonding level found at the valence-band edge may cause lattice trapping of valence-band holes. © 1971 The American Physical Society.