Analysis of conduction mechanisms in alumina-filled epoxy resin under dc field and temperature

The electrical behavior of an alumina-filled epoxy resin is investigated in view of its use in high voltage applications. Current-voltage characteristics obtained under dc electric fields comprised between 1 kV/mm and 40 kV/mm, at temperatures from 20°C to 105°C, are analyzed. An ohmic behavior is observed at low fields (<;4 kV/mm) across the entire temperature range. At high field, a volume-controlled conduction mechanism (space charge limited currents) is put into evidence below 85°C, and an interface-controlled mechanism (heterocharge-assisted Schottky injection) is found to be predominant at 105°C.