Electron trapping in SiO2—An injection mode dependent phenomenon

Electron trapping in metal-oxide-silicon structures and its dependence on the injected electron energy distribution and oxide field were studied. It is found that at high injection levels trapping efficiency and saturation level increase with the accelerating field in the Si, and decrease with increase in the oxide field. These results differ markedly from those obtained in low level injection, in which it is assumed that trapping is of electrons injected from the Si into the oxide conduction band. Based on the high level injection experimental results, it is proposed that significant electron trapping is obtained through direct tunneling of hot electrons with energy less than the potential barrier, into localized states in the oxide near the Si-SiO2 interface.