Photoemission of Electrons from Silicon and Gold into Silicon Dioxide

Photoemission of electrons from both silicon and gold into thermally grown silicon dioxide layers has been observed. In each case, the energy threshold for photoemission is found to vary with the electric field in the oxide. Within experimental error, this variation is consistent with the theoretical Schottky effect, assuming an effective value of image-force relative dielectric constant of about 2.15. The extrapolated zero-field threshold energies for silicon and gold are about 4.2 and 3.8 eV, respectively. From measurements of the photocurrent versus electric field, it is inferred that for electrons in the oxide conduction band, the product of mobility and mean time before immobilization by deep trapping is of the order of ${10}^{-13\mathrm{}}$ ${\mathrm{m}}^2$/V.