Photoconduction in kapton polyimide film at high electric fields

Photoconductivity in kapton polyimide film in the visible region is studied under steady state conditions in the temperature range of 100 to 200 °C and at electric fields of 60 to 450 kV/cm. An attempt is made to fit the field dependence of the photocurrent to one of the several possible conduction mechanisms which are proposed by different workers. Evidence is presented to suggest that at high electric fields as at low fields the conduction in kapton is ionic in nature. Values of ionic jump distance of 68 to 84 Å and apparent activation energy of photocurrent at zero field of 1.04 eV are obtained. These values are shown to fit the ionic conduction hypothesis.