Dynamic charging characteristics of nano-doped polymers under tens of keV electron irradiation

The dynamic charging characteristics of polymers doped with nanoparticles under electron irradiation are still unclear. A numerical model combining electron scattering, drift, diffusion, and deep trap is constructed in this work. The dynamic characteristics of space charge distribution, potential distribution, and the electron beam induced current (EBIC) are obtained. Results show that, due to the emission of secondary electrons from the surface, the net charge near the surface is approximately neutral, but the internal negative charge exhibits a maximum value. Under long time irradiation, the surface potential, EBIC, and the emission current tend to reach equilibrium. The increase in deep trap density caused by nanoparticle doping leads to the decrease in charge transport, resulting in the accumulation of negative charges, which causes the increase in negative potential and a corresponding decrease in EBIC. With increasing the film thickness the negative surface potential increases while the EBIC decreases.