Concentration and mobility of charge carriers in thin polymers at high temperature determined by electrode polarization modeling

Charge carrier concentration (n0) and effective mobility (μeff) are reported in two polymer films (<10 μm) and in a very high temperature range (from 200 to 400 °C). This was possible thanks to an electrode polarization modeling of broadband dielectric spectroscopy data. It is shown that the glass transition temperature (Tg) occurrence has a strong influence on the temperature dependence of n0 and μeff. We carry out that n0 presents two distinct Arrhenius-like behaviors below and above Tg, while μeff exhibits a Vogel-Fulcher-Tamman behavior only above Tg whatever the polymer under study. For polyimide films, n0 varies from 1 × 1014 to 4 × 1016 cm−3 and μeff from 1 × 10−8 to 2 × 10−6 cm2 V−1 s−1 between 200 °C to 400 °C. Poly(amide-imide) films show n0 values between 6 × 1016 and 4 × 1018 cm−3 from 270 °C to 400 °C, while μeff varies between 1 × 10−10 and 2 × 10−7 cm2 V−1 s−1. Considering the activation energies of these physical parameters in the temperature range of investigation, n0 and μeff values appear as coherent with those reported in the literature at lower temperature (<80 °C). Surface charge carrier concentrations (nS) are reported and discussed for potential passivation (i.e., surface electrical insulation) applications. Polyimide films appear as good candidates due to nS values less than 1011 cm−2 up to 300 °C.