Electrical conduction in parylene HT: transient and steady-state analyses at high temperature

The electrical conduction of Parylene HT films, a high performance fluorinated parylene, is investigated at high temperature (200 to 350 °C), high electric field (5 and 360 MV/m) and for different thicknesses (1.2 to 5 μm). The steady-state currents are analyzed by assuming different conduction models. Whereas the Schottky and Poole- Frenkel models are the less probable, the thermally assisted hopping mechanism appears as the most probable conduction mechanism for fields up to the threshold (~150 MV/m). Based on the analysis of the hopping jump distance and its evolution versus temperature, an ionic hopping conduction has been proposed as the most probable charge carriers´ origin to describe our results. Finally, the film thickness and the field polarity are studied. Results indicate that positive carriers (holes) are the main contributors to the injection current for high electrical fields.