A direct proof of charge injection/extraction at the metal-dielectric contact

The problem of charge injection/extraction at a metal- dielectric contact is treated theoretically by analogy with that for a metal-semiconductor contact. However, because in a dielectric material there is a large number of surface traps and bulk traps, the electrical conduction through a dielectric material is bulk limited and electrode limited and it is difficult to discriminate between the electrode effects and the bulk effects and to have detailed information only about one of the mechanisms. We propose a method that allows to determine the value and the sign of the electric charge injected/extracted at the metal-dielectric contact. The method is based on the modification of the external electric field of a dielectric when electric charge is injected or extracted into or from it surface, respectively, as consequence of an applied electric field at the contact between dielectric and metal.