A theory of localized electronic breakdown in insulating films

Abstract A review of measured breakdown properties in insulating films and of electronic theories of breakdown shows both theoretical and experimental inconsistencies. A theory is proposed in which electronic breakdown is caused by local chance events, such as a succession of avalanches at one spot. Successive avalanches sustain the growth of space charges, the local cathode field, and the avalanche rate. When the cathode field becomes large enough to make continuation of avalanching a certainty, instability with current runaway arises, causing breakdown. According to theory, breakdowns occur over a range of fields, their chance increasing very strongly with field; the breakdowns occur randomly in space and in time; the time to instability on a breakdown event decreases as some exponential function of increasing field; the breakdown field can both increase and decrease with temperature; it may be electrode dependent, and it decreases first rapidly and then more slowly with increasing film thickness. Observations made in a number of insulating films support the proposed theory.