Electrical Breakdown: I . During the Anodic Growth of Tantalum Pentoxide

Abstract

Observations are presented on breakdown events during the anodic growth of tantalum pentoxide in characteristics which plot the rate of breakdown as function of oxide thickness at constant field, . The characteristics shift to lower thicknesses for an increase in field, or a decrease in temperature. The breakdown process is interpreted by the stochastic succession of avalanche breakdown model. An approximate relation was derived for the rate of breakdown as function of insulator thickness. This relation could be well fitted to experimental data at various fields. The fitting procedure permits the evaluation of the coefficient of impact ionization α, finding for a set of anodizations with in MV/cm, in the range of fields 6.1–6.7 MV/cm. There is an uncertainty of roughly ±10% in α, due to shallow minima in fitting procedures, to fluctuations in the rate of breakdown, and to some uncertainty in the magnitude of .