A Model for Dielectric Breakdown in Plasma-Polymerized Styrene Thin Films

Abstract

A new, simple breakdown model is presented as a result of experiments on plasma-polymerized styrene thin films. In this model, the current is controlled by Fowler-Nordheim tunnelling emission from the cathode, and bulk breakdown is governed by an impulse thermal process. The numerically-calculated values, disregarding the space charge, can be fitted to the dependence of the electric strength on temperature, field rise rate and prestress and are also consistent with all the experimental results. Also, steady-state avalanching is considered as a possible mechanism for bulk conduction. It is found that provided the mobility of positive charges is beyond a certain value, hardly any space charge is formed, giving a physical basis for neglecting the space charge. Also, impulse thermal breakdown can occur before a negative resistance appears. The parameters involved in the model are also discussed.