Monte-Carlo simulation and experimental study of the effect of internal charging on the electron emission yield of amorphous SiO2 thin films

Abstract

A Monte-Carlo code has been developed for the transport of low energy electrons and the simulation of the internal charge buildup induced by the electron irradiation in thin films of amorphous SiO2. The code is validated with time resolved experimental Electron Emission Yield (EEY) data on 20 nm SiO2 thin films for incident electrons of 300 eV and 1 keV. As the EEY is greater than 1, this corresponds to the case of positive charging. In order to assess the impact of the charge buildup on the electron emission yield, the samples have been negatively polarized to suppress the positive external charging effects, and irradiated with a defocused beam (mm²). A direct correlation is found between the value of the EEY and the density of holes created in the material. This clearly shows that the recombination of the secondary electrons with trapped holes significantly affects the EEY of insulators.