Dynamic investigation of the trapping properties of electron irradiated dielectrics in a SEM

A method is described that allows the amount of trapped charge in insulating materials during their electron irradiation in a scanning electron microscope (SEM) to be provided and the charge mechanisms regulation to be understood. The trapped charge regulation mechanisms involve several parameters related to the electronic injection, the characteristics of insulator and the effects of the trapped charge itself. For that purpose we propose an arrangement adapted to the SEM in order to measure, one among these parameters, the leakage current and also the displacement current. The dynamic trapping properties of glass-ceramic are investigated and the time constants for charging and discharging processes are evaluated. By correlating the leakage and displacement currents, the total electron yield σ during irradiation is also determined.