Precise Evaluation of Charging Effect on SiO₂ Particles by Simulation of Holograms

Abstract

The charging effect due to the electron irradiation in spherical SiO₂ particles of 250 nm in diameter has been analyzed by electron holography. Electron holograms of a charged SiO₂ particle on the side surface of the carbon film were simulated taking into account the electric shielding effect due to the carbon film. In order to compare the observed hologram and the simulated holograms quantitatively, the residual index between the observed and simulated images was evaluated. Through the quantitative analysis taking into account the shielding effect with the limited side surface area of the carbon film, the amount of the charge was evaluated to be 3.38×10⁻¹⁷ C for the current density of incident electron beam at 0.24 A/m² without an objective aperture.