Influence of the electrode metal on the injection of space charges in PET and epoxy resin

Using the LIPP method, negative homocharges have been observed in PET sheets after a few hours poling under 6kV/mm DC at 60 °C. This observation was made with various electrode metals: gold (Au), aluminium (Al) and silver (Ag). With gold electrodes, the injection is much slower than with the other two metals. Furthermore, the gold metallization is the only one leading to the injection of positive space charges in the same conditions. Similarly, at 55 °C under 7kV/mm, positive homocharges have been observed in epoxy sheets only with gold-deposited electrodes and not with aluminium electrodes.