Charge injection and transport in dielectrics: Myths and reality

Charge injection and transport processes in dielectrics have been extensively studied and discussed over the years(1). They have been tentatively described by a wide variety of theoretical models. Although these theories partially describe actual experiments, they rarely give a complete and unequivocal explanation of the observed phenomena. One objective of this paper is to make a critical review (relying on existing data) of some often used models and also to point out their limits of validity. It will be shown that many results cannot be described by a given model either because the basic requirements of this model are not fulfilled or either, because another theory would give a much better fit to experimental results. Another objective is to briefly discuss the nature of charge carriers in polymer dielectrics. Ionic measurements obtained with recently developed ion chromatographs are presented and discussed.