Visualization using scanning nonlinear dielectric microscopy of electrons and holes localized in the thin gate film of a metal–SiO₂–Si₃N₄–SiO₂–semiconductor flash memory

We have used scanning nonlinear dielectric microscopy to clarify the position of electrons and holes in the gate SiO₂–Si₃N₄–SiO₂ (ONO) film of a metal–ONO–semiconductor flash memory. The electrons were detected in the Si₃N₄ part of the ONO film, while the holes were found in the bottom SiO₂ film as well as in the Si₃N₄ film. This suggests that the injected electrons and holes did not always recombine with each other.