Charging effect and relaxation processes in electron bombarded cryogenic solids

Charging effect and relaxation processes in cryogenic solids pre-irradiated by an electron beam are discussed with the example of solid Xe. The experiments were performed employing combination of the cathodoluminescence method with activation spectroscopy techniques: thermally stimulated luminescence (TSL) and thermally stimulated exoelectron emission (TSEE). Relaxation emissions of photons and electrons were detected in the time correlated manner. A long-lasting “afteremission” of electrons and afterglow of VUV photons were observed on completing irradiation. The experiments performed with a variable voltage applied to the Faraday plate enabled us to demonstrate appreciable accumulation of electrons and ascertain the spatial distribution of the charge centers. The uncompensated negative charge is found to be localized preferentially near the surface. Xe layers close to the sample-substrate interface are shown to be positively charged. The part played by pre-existing and radiation-induced defects as well as dopants is considered and the temperature range of the electron traps' stability is elucidated.