Papers by Keyword: Charging Effect

Abstract: The paper is devoted to developing the theoretical basis of the mathematical modelling and computer simulation intended to analyze and control the electron beam-stimulated effects in ferroelectric materials. In order to simulate the electron beam-induced charging dynamics of ferroelectrics the modification of drift-reaction-diffusion model was proposed. The calculation was based on the numerical solution of the continuity equation and Poisson equation. The parameters of the electron irradiation doze and source function were estimated by 3D Monte-Carlo simulation of electron trajectories in the solid specimen. The computation was associated with typical ferroelectrics (LiNbO₃, LiTaO₃) irradiated by intermediate-energy electron bunches specified for SEM. The contribution roles of drift component as well as diffusion component during dynamic charging process were discussed. The simulation results enable us to predict charge distribution, dynamic of the potential distribution, electric field and electron beam-induced component of polarization at the given experimental parameters. These findings can be used to control polarization switching in ferroelectrics electron beam-irradiated by the SEM techniques.

Abstract: The paper presents results of a computer simulation of dynamic processes caused by electron injection and charging-up effects in ferroelectrics irradiated by electron bunches with average energy. The implementation of electron transport simulation in ferroelectrics was performed by Monte-Carlo method to express the initial volume charge distribution. The calculation of charging characteristics was based on solution of Poisson equation using finite element method. The calculated distribution of potential as well as field intensity electron beam-induced for model sample were analyzed at given experimental parameters.

Abstract: The charging effects on non-conductive materials due to electrons irradiation were investigated by electron holography. The phenomena that the charging effects were more enhanced with an increase in the incident electron density were visualized through the direct observations in the electric potential distribution around the specimens. In addition, through the comparison between the electron holography results and the simulations, we were able to obtain the quantitative results indicating the amount of charges accumulated during electron irradiation.

Abstract: X-ray photoelectron spectroscopy (XPS) has been used to characterize the Si nanocrystals (nc-Si) incorporated in SiO2 by ion implantation and subsequent thermal annealing. XPS results suggest that the as-implanted films contain a composition of a few suboxide SiOx (x<2). The dependence of XPS spectra on annealing temperature show that these suboxides decompose into SiO2 and Si nanocrystals. Due to the implanted Si+ depth profile, thermal annealing will lead to the formation of nc-Si with different sizes corresponding to the depth. Si0 peak shifts arising from the size effect of nc-Si can be clearly observed. Photo-induced charge effect from the nc-Si has been studied in this work. The potential wells induced by nc-Si in the SiO2 band gap substantially enhance the charging effect, which causes a significant shift in Si0 and C1s core levels.