Oxide-Charge-Induced Impurity Level in Silicon Inversion Layers

We have observed a peak in the conductivity-versus-gate-voltage curves for n-channel silicon metal-oxide-semiconductor field-effect-transistor devices containing large oxide-charge densities, 4.7×1011Acm-21.1×1012Acm-2. This peak is interpreted as an oxide-charge-induced impurity level within the lowest sub-band tail. It is found that the impurity level contains one electron state for each oxide charge situated at the Si-SiO2 interface. © 1975 The American Physical Society.