Intrinsic breakdown refers to the electric field which will
cause breakdown of a “perfect” material in a very short time,
i.e., without the effects of high field aging. The measurement of
intrinsic breakdown is always problematic, as “perfection,” even
in crystalline materials, is difficult to achieve on a macroscopic
basis. Electrode–material interfaces are never “perfect,” and, in
principle, the position of the electrode Fermi level within the
band gap and relative to impurity states can affect the break-
down field. Thus when metallic electrodes are employed, many
tests must be carried out, and the intrinsic breakdown field is
taken as the upper limit of the experimental data. More recently,
intrinsic breakdown has been measured using an intense optical
field, which, for transparent materials, avoids electrode effects.