Visualization using scanning nonlinear dielectric microscopy of electrons and holes localized in the thin gate film of a metal- SiO2 - Si3 N4 - SiO2 -semiconductor flash memory

We have used scanning nonlinear dielectric microscopy to clarify the position of electrons and holes in the gate SiO2 - Si3 N4 - SiO2 (ONO) film of a metal-ONO-semiconductor flash memory. The electrons were detected in the Si3 N4 part of the ONO film, while the holes were found in the bottom SiO2 film as well as in the Si3 N4 film. This suggests that the injected electrons and holes did not always recombine with each other.