Formation and destruction of polarization by migration of space charge

In a thermal electret of a polymer, excess charge, which is released from traps at high temperature, migrates in the polymer and forms a polarization under an applied electric field. We treat the density distribution of excess carriers by computer simulation calculation. Using a simple model of monoenergetic trap and monoenergetic transport states, we could explain the behavior of excess carriers in the process of polarization and depolarization. The calculations show that the excess charge gathers at the extreme end of a domain by the process of poling and that the accumulated charge hardly diminishes by the process of depolarization