Determination of the electron beam irradiated area by using a charging effect in oxide surfaces

The further characterization of charge dynamics in non-conductive materials using the electron beam of the scanning electron microscope requires knowledge of the beam current and the injected charge densities. We report in this work an experimental procedure based on the charging effect of oxide surfaces allowing a direct determination of the size of the area irradiated by the incident defocused beam. This procedure derives from previous results recently obtained using the electron beam lithography technique. We found that the performance of this new method is restricted by the ability of the oxide to trap a sufficient amount of charge and to keep them localized. The method was successfully applied to MgO and Al2O3 single crystals and MgO layers.