A new method for charge trapping measurement during electron beam irradiation: application to glass containing alkali ions and single-crystalline quartz

Abstract

The aim of this work is to study the electron irradiation behaviour of an insulating material surface using a scanning electron microscope (SEM). The charging phenomena caused in two kinds of insulating materials (quartz and glass) by continuous electron irradiation have been observed. The discharging phenomena following switching off of irradiation have also been studied. The trapped charge density is determined by using the so-called electrostatic influence method based on the measurement, during and after the irradiation, of the influence and leakage currents using an arrangement adapted to the SEM. The experimental results reveal that the behaviour under irradiation of glass is entirely different from that of quartz. The trapped charges are found to be different, and the dependence of charging on the primary beam energy is discussed.The charging and discharging time constants have been determined accurately, and their evolution versus the mean electron penetration depth is qualitatively explained. Moreover, the role of secondary electron emission in the regulation mechanism of charging is underlined.

Charge regulation mechanism of grounded-coated insulators

“…This time constant, decreases with the increase of the primary energy. The decrease of is related to the increase of electric field assisted migration of sodium ions towards the bulk which induces a conductivity rise, leading to the emphasis of the trapped charge release [12]. Hence, the rise of the conductivity will lead to the shortest time to reach the saturation of trapped charge when the primary beam energy increases.…”

“…When the primary beam energy increases (increase of the mean-electron penetration-depth), an increase of is observed. This is due to the fact that the released charge is evacuated to the ground following both the surface (below the grounded coating) channel and the bulk channel of the sample [12]. The characteristic time of discharging ' (see Table. 2) decreases with the increase of the primary beam energy.…”

“…In fact when the energy of incident electrons increases, their range increases also and more charges are trapped in deepness in the sample producing an increase of the strength of electric field which when it reaches a critical value triggers the detrapping process via the conductive coating. Therefore the leakage current (ionic and electronic currents) [12] through the volume of the material and along its surface (below the grounded coating) increases leading to a decrease of time constant.…”

An algorithm for removing charging effects from X-ray photoelectron spectra of nanoscaled non-conductive materials

“…Here, δ(ΔE S-S ) is a delta function whose argument is the steady-state value of the electrostatic surface potential (i.e., charging of the surface) when the sample is exposed to X-ray radiation. The steady-state surface electrostatic potential is reached for a very short time after the source is switched on [26][27][28] and it can remain stable and constant during spectrum collection via compensation mechanisms [12]. Moreover, this condition means that the integration of equation (3) over the time for which the spectra are collected will produce the same result, which is formally «Φ(E) → δ(ΔE S-S )» (Fig.…”

The assessment of microscopic charging effects induced by focused electron and ion beam irradiation of dielectrics

“…Charged beam irradiation of electrically insulating materials may result in the trapping of charge within an irradiated/implanted specimen. Electron beam irradiation induced charging in a scanning electron microscope (SEM) has been shown to result in localized (micro-) modification of insulating bulk specimens (Cazaux, 1986(Cazaux, , 1996Fakhfakh et al, 2004;Stevens-Kalceff, 2001, 2004. Focused ion beam induced localized specimen charging has also been observed .…”