Electron traps and excess current induced by hot-hole injection into thin SiO2 films

Electron capture and excess current after substrate hot-hole injection into 60 and 131 Angstrom silicon dioxides have been studied. After the hole injection into 131 Angstrom oxides, a transient excess current appears in the gate current-oxide field characteristics and electrons are captured even at low oxide fields for the positive gate polarity. The low field electron capture is explained based on the tunneling of electrons from the substrate into the positive charge and neutral trap centers created near the substrate-SiO2 interface. The transient excess current is suggested to be due to the two current components: the displacement current component due to the electron capture by both the positive charge and the neutral trap centers, and the tunneling current component enhanced by the positive charge located near the interface. In 60 Angstrom oxides, excess currents appear for both positive and negative gate polarities after the hole injection, and consist of the steady-state leakage current component and the transient current component. The leakage current induced by the hole injection is increased as the oxide thickness is decreased.