Charge injection from polycrystalline silicon into SiO₂ at low fields

Electron injection from polycrystalline silicon into thermal SiO 2 at low fields is observed in polycrystalline-silicon-SiO 2-Si capacitors. C-V, pulsed-charge injection, and charge-relaxation measurements show that the injected electrons are captured by centers in the SiO2. These trapping centers appear to be located at about 30 Å from the polycrystalline-silicon-SiO2 interface and are characterized by an energy level approximately 0.3 eV above the Fermi level of the degenerate n-type polycrystalline silicon. Annealing of the samples in nitrogen or forming gas strongly affects the charge injection.