Return voltage measurements: Theory and applications to charge injection monitoring

Charge injection is in many cases a step towards the breakdown of insulating materials. Although modern charge mapping techniques exist, they might be too expensive or difficult to use in an industrial laboratory environment, and an alternative solution for charge injection monitoring, especially on thin films, could be measurements of the return potential. The return voltage occurs when an insulator charged during a period of time cannot be neutralized by a short circuit whose duration is short compared to the charging time. Either relaxation of slow dipolar movements, or the return towards the electrodes of a dissymmetrical internal space charge distribution can be held responsible for the return potential. Charge injection from the electrodes usually gives birth to such a dissymmetrical distribution (though not necessarily).