Ionization mechanism of electrical breakdown in polymers. Effect of potential barrier shape and charge mobility

Results are presented to confirm the ionization mechanism of electrical breakdown in polymers. The use of a triangular or Coulomb barrier for electron tunneling in calculations leads to significantly different lifetimes (time to breakdown) for polymers in an electric field. A sharp decrease in lifetime (a jump) with increasing electric field strength was observed for both barriers. The jump is characterized by an abrupt transition between two smooth lifetime lines—a top and a bottom one. The difference between the top and bottom lines can reach several orders of magnitude. Analytical formulas for the equations of the lifetime lines have been derived. The experimentally recorded jump in lifetime for polyethylene terephthalate demonstrates the feasibility of the ionization mechanism of polymer breakdown.