High-thermal-resistant electrical insulation deposited by plasma polymerization

Thin films of high-thermal-resistivity electrical insulation were prepared by plasma polymerization of silazane and subsequent pyrolysis in air up to 1500 K of the deposited polymer. The chemical constitution of the films transforms into a silicon oxide type and a polycrystalline structure occurs after pyrolysis. The electrical properties of this material were intensively investigated. The symmetrical-Schottky-barrier model was proposed for description of the electrical conductivity. It has been found that above 400 K the thermionic emission mechanism dominates whereas at lower temperatures the transport is governed by the thermionic field emission. The deformation of the polycrystalline structure was observed upon application of an external electrical field. This process causes an increase of the conductivity. It is concluded that the thin coatings obtained by pyrolysis in air of plasma polymerized silazane films are characterized by strong adhesion to kanthal surfaces, high thermal resistivity, and very good insulating properties in a broad range of temperatures