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

Charge carrier concentration (n(0)) and effective mobility (mu(eff)) are reported in two polymer films (<10 mu m) and in a very high temperature range (from 200 to 400 degrees C). This was possible thanks to an electrode polarization modeling of broadband dielectric spectroscopy data. It is shown that the glass transition temperature (T-g) occurrence has a strong influence on the temperature dependence of n(0) and mu(eff). We carry out that n(0) presents two distinct Arrhenius-like behaviors below and above T-g, while mu(eff) exhibits a Vogel-Fulcher-Tamman behavior only above T-g whatever the polymer under study. For polyimide films, n(0) varies from 1 x 10(14) to 4 x 10(16) cm(-3) and mu(eff) from 1 x 10(-8) to 2 x 10(-6) cm(2) V-1 s(-1) between 200 degrees C to 400 degrees C. Poly(amide-imide) films show n(0) values between 6 x 10(16) and 4 x 10(18) cm(-3) from 270 degrees C to 400 degrees C, while mu(eff) varies between 1 x 10(-10) and 2 x 10(-7) cm(2) V-1 s(-1). Considering the activation energies of these physical parameters in the temperature range of investigation, n(0) and mu(eff) values appear as coherent with those reported in the literature at lower temperature (<80 degrees C). Surface charge carrier concentrations (n(S)) are reported and discussed for potential passivation (i.e., surface electrical insulation) applications. Polyimide films appear as good candidates due to n(S) values less than 10(11) cm(-2) up to 300 degrees C. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733946]