High field prebreakdown aging in polymer dielectric thin films

Fundamental understanding of carrier mobility-centric prebreakdown phenomena in dielectrics provides insights into high field aging and onset of charge injection instability. Dielectric degradation, which eventually culminates in breakdown, is essentially the progressive creation and accumulation of atomic and nanoscale defects, assisted by electric field, time and temperature. Despite intensive previous research, the behavior of a material experiencing enormous electric fields still lacks fundamental understanding. In this study, we present our investigation of prebreakdown field aging of polymers under various conditions, with an attempt to pin-point the conditions that lead to defect creation under high field. An automatic breakdown measurement setup was purposely developed for prebreakdown aging study to collect large numbers of data points under each prebreakdown aging condition for statistically meaningful Weibull analysis. A threshold field was found in PS above which the polymer undergoes rapid degradation assisted by the electric field. The ability to pin-point the condition for rapid defect creation under high prebreakdown fields sets the stage for advanced characterizations of their physical natures and molecular origins. This work marks a significant step towards fundamental understanding of aging in dielectrics under extremely high electric fields.