Fowler-Nordheim Tunneling into Thermally Grown SiO2

TLDR

Electronic conduction in thermally grown SiO₂ is limited by Fowler‑Nordheim tunneling from the electrode Fermi level into the oxide conduction band, a mechanism observed over five decades of current in Si, Al, and Mg. The analysis incorporates image‑force barrier lowering and temperature corrections. Using measured barrier heights, the study finds a relative effective mass of ~0.4 from Fowler‑Nordheim slopes, observes current magnitudes five to ten times lower than theory likely due to trapping, confirms temperature dependence from 80–420 K (though an effective mass of ~0.95 is required), and presents the most comprehensive examination of the theory.

Abstract

Electronic conduction in thermally grown SiO2 has been shown to be limited by Fowler-Nordheim emission, i.e., tunneling of electrons from the vicinity of the electrode Fermi level through the forbidden energy gap into the conduction band of the oxide. Fowler-Nordheim characteristics have been observed over more than five decades of current for emission from Si, Al, and Mg. If previously measured values of the barrier heights are used, the slopes of the Fowler-Nordheim characteristics (log J/E2 vs 1/E) imply values of the relative effective mass in the forbidden band of about 0.4. These values take into account corrections for image-force barrier lowering and for temperature effects. The absolute values of the currents are lower by a factor of five to ten than the theoretically expected values, probably due to trapping effects. The temperature dependence of the current was found to follow the theoretical curve from 80°–420°K. However, an inconsistent relative effective mass of about 0.95 had to be assumed. These results are believed to provide the most complete examination of the Fowler-Nordheim-emission theory.