Importance of charging conditions on charge trapping in electrets

The charging of a polymer film is the basic process in the formation of an electret, both electrostatic and piezoelectric types. Charging may be performed by many techniques[1] such as by electron beam bombardment, by the liquid contact method, by corona charging, by thermal poling and in an ionization chamber[2] The corona charging technique is similar to the thermal poling method except that only one electrode is required before poling. Differences, however, are likely in the nature of the injected charges due to the different ionic species available for injection.