Bipolar Charge Transport Model with Trapping and Recombination: An Analyze of the Current vs. Applied Electric Field Characteristic

A bipolar model of transport intended to describe the behaviour of polyethylene in steady state is presented. The model is based on Poisson´s equation and the conservation law of charges, trapping, detrapping and recombination phenomena being taken into account. Electric field and carrier concentrations are formulated for double-carrier injection and boundary conditions are given by the Schottky injection law. The current vs. applied electric field characteristic is obtained and analyzed in order to understand the influence of the parameters on the different slopes of this curve. Results show that the recombination plays an essential role in order to obtain the 2 changes in slope - forming a sigmoid-like shape of the characteristic as observed experimentally in this kind of material.