Comparison of Bare and Metallized-Grounded Soda-Lime Glass under 20 keV Electron Beam Irradiation in SEM: Charge Trapping and Sodium Ion Migration - Taktak, Sirine; Fakhfakh, Slim; Jbara, Omar (Journal of Electronic Materials, 2026)
This work presents a detailed experimental analysis of trapped charge accumulation and internal electric field enhancement in soda-lime glass insulators subjected to electron beam irradiation, comparing bare samples with those coated by a thin grounded metallic layer. Surface charge density measurements were conducted using the electrostatic induction method, with irradiation performed inside a scanning electron microscope (SEM). Sodium ion migration during irradiation was monitored using an energy-dispersive x-ray spectrometer (EDXS). Under 20 keV irradiation, electrons implant negative charge in the glass bulk, creating an internal electric field. In the ungrounded sample, this field saturates at equilibrium and vanishes quickly when the beam stops, so Na $$K_{\alpha }$$motion halts during the beam-off period. In contrast, the grounded sample sustains a strong field from the stored charges that persists without beam, driving continued Na $$K_{\alpha }$$migration. Hence, only the grounded (gold-coated) glass shows additional Na depletion (reduced Na x-ray signal) after the pause, while the bare glass does not. This explanation is supported by charge injection physics and observed alkali migration in soda-lime glasses under electric fields.The findings not only challenge conventional assumptions about the role of metallization in charge control but also provide new insights into the behavior of insulating materials under electron irradiation. This has direct implications for accurate SEM-based characterization, particularly for materials prone to ionic migration, and for the design of advanced insulating components in high-radiation environments such as space systems, electron-optical devices, and high-voltage power applications.
Keywords: journalArticle; Coated glass; SEM; electron irradiation; electron–matter interaction; trapped charge; uncoated glass