Electrical properties of ultra thin polypropylene film

Ultra thin polypropylene (PP) films (thickness: 10~100 nm) are deposited on a glass substrate by the vacuum evaporation method. The temperature of the glass substrate is kept at room temperature or 100°C during the deposition. The ESCA data revealed that a ultra thin PP film (thin PP film) is not only oxidized on the surface but also in the bulk. The oxidation effect or breakdown strength of thin PP film is discussed and its electrical conduction may be explained by Schottky or tunneling injection. The electric field strength of a 7.8 nm thick PP film is 10 MV/cm at an effective electrode area of 98% after self-healing breakdown and that of a 6.5 nm thick PP film is 6 MV/cm. This means that the weak points of a 6.5 nm thick PP film are fewer than that of a 7.8 nm thick PP film. The electric field strength of a 6.5 nm thick PP film is 15 MV/cm at an effective electrode area of 64%