Effect of field-dependent mobility on current density and dynamics of space charge in polyethylene

Transient space charge within polyethylene has been simulated based on a bipolar charge transport model with a constant mobility. Initial results are in good agreement with those previously reported. To further develop the model, two types of field-dependent carrier mobility: power-law mobility and Poole-Frenkel mobility are considered in the charge transport process. Various space charge profiles and the current densities under different dc voltages have been achieved by using the simulation. The resulting current density vs. the applied electric field under different mobility models has been discussed. The results show that power-law mobility is a good alternative for simulating field-dependent charge behavior even though Poole-Frenkel mobility presents stronger field-dependent characteristics.