High field conduction in poly-p-xylylene thin film

Poly-p-xylylene (PPX) films prepared by thermal chemical vapor deposition showed a negative temperature dependence of high-field current, dJ/dT<0, in the low-temperature region. The high-field current was accompanied by electroluminescence (EL). These results are explained in terms of collision ionization. In poly-2-chloro-p-xylyene (PCPX) films, which had a chlorine atom in a monomer unit, high-field current and EL were suppressed. Similar phenomena were observed on PPX films treated by an RF plasma. These films showed a higher breakdown strength than PPX films. It is concluded that chlorine atoms or defects introduced by the plasma treatment act as scattering centers and suppress the collision ionizations.<>