Electrical properties of ultra thin evaporated polypropylene films

A ultrathin polypropylene film (PP film) is deposited on a glass substrate from an evaporating source in vacuum. The temperature of the glass substrate is kept at 100/spl deg/C during the deposition. The thin PP film is about 100/spl Aring/ in thickness. The film shows a self-healing breakdown in the high field region, and the electrode area gradually decreases. The electric strength of the film was 12.2MV/cm after self-healing breakdown. Its value is higher by a factor 1.7 than that of a conventional film. The conduction current in the ultrathin film is ohmic in the low field region and increases steeply by tunneling injection in the high field region.<>