Role of Core Levels’ Ionization in the Electron Induced Dissociation of Silicon Dioxide

Abstract

Desorption of ions and neutrals from surfaces under low energy (a few keV) electron or photon irradiation has long been recognized as due to electronic excitations not only from the outer valence levels involved in the bonding, but also from the inner levels. The latter observation goes back to the work of Knotek and Feibelman [1]. In the original formulation of the model proposed by these Authors (KF model), the states leading to desorption are generated via inter-atomic Auger transitions following core ionizations. As such, the model is strictly applicable only to maximal valency ionic compounds, that is when the cation is nominally ionised down to the noble gas configuration. However, it was soon recognized that possible desorptive states can be generated via Auger transitions in covalent systems too [2]: intra-atomic transitions are involved and correlated final state valence holes are required to make Auger Induced Desorption effective in this case [3].