Dynamics of nonlinear charge injection in polymeric films

Abstract

Fundamental understanding of carrier mobility-related pre-breakdown phenomena in dielectrics provides insights into high field transport phenomena as well as the associated aging and onset of charge injection instability. A system for measuring resistive current through a planar dielectric film during a linear ramp voltage to breakdown has been developed to address the limits of conventional steady-state approaches in which the sample typically fails at ∼60% of the breakdown field. With a dynamic range of 140dB and high linearity of the feedback loop, the system can facilitate cancelation of capacitive current during even substantial changes in sample capacitance as a function of field, which can occur in highly nonlinear materials. Based on this technique, the pre-breakdown conduction in polymeric films was characterized, which suggests highly nonlinear field dependence of charge injection and transport. Ability of such transient measurement of the dynamics of nonlinear charge injection in polymeric films provides a basis for conduction mechanism study and material engineering for improved high field performance.