Generation of positive charge in SiO2 thin films during electron irradiation

The positive shifts in the energy position of the Si(L2,3VV) Auger peak produced by 1–3 kV electron irradiation of SiO2 thin films have been quantitatively explained as related to the electron trapped charge distribution. However, the electron beam also induces negative Auger shifts for certain experimental conditions. This result is interpreted in terms of a buildup of positive charge, associated to the bond breaking processes in the oxide bulk, with a formation cross section σf+≊10−17 cm2. The centroid of the spatial positive charge distribution depends on the primary beam energy, and it is not necessarily located at the SiO2/Si interface.