Charge transport and accumulation in dielectrics upon irradiation by an electron beam

Abstract

The transient process of charge accumulation in a dielectric with exposed surface is considered for the case of irradiation by a beam of electrons with path lengths less than the specimen thickness. For the case of shallow traps the characteristic method is used to solve the problem of passage of the space charge density front through the specimen volume from a virtual cathode located at a depth equal to the path length of the primary beam electrons to a grounded electrode. Transient patterns of field intensity and space charge density over dielectric layer thickness are found. Special features of the transient process are considered, related to the fact that the charge carriers are being injected into the dielectric by an electron beam. Furthermore, an expression is obtained describing the kinetics of formation of the exposed dielectric surface potential, and the dependence of these kinetics on radiation parameters and dielectric properties are considered. The conclusions of the model are compared to experiment.