Breakdown and Prebreakdown Phenomena in Solid Dielectrics

In this review we concentrate on simple phenomenological models which lead to testable predictions. We discuss inhomogeneous field situations since in practice breakdown and aging starts as points of local field enhancement. The well known space-charge-limited-current model is generalized in several steps to field-dependent mobility, negative differential resistance and impact ionization. A fractal model for breakdown is introduced. The model contains a small number of physically transparent parameters.